Belly pain is common and, most of the time, doesn't have a serious cause.

Abnormality of gait (or gait abnormality) is an unusual walking pattern or style.

An abrasion is a minor scrape of the skin that can be treated easily with proper cleaning and care.

An abscess is a collection of pus that forms as part of the body's response to an infection.

See: Abscess, Periapical.

A skin abscess forms when bacteria get under the skin.

A tooth abscess is a collection of infected material (pus) that forms at the tip of the root of a tooth.

Physical abuse can be any kind of hitting, shaking, burning, pinching, biting, choking, throwing, beating, and other actions that cause physical injury, leave marks, or cause pain.

Psychological abuse happens when yelling and anger go too far or when people caring for kids constantly criticize, threaten, or dismiss them until their feelings of self-worth are damaged.

Sexual abuse is sexual contact with a child or any behavior that is meant to sexually arouse the abuser.

Substance abuse is when someone drinks alcohol or smokes or takes drugs in a way that could lead to health, legal, and other problems.

Acanthosis nigricans is a condition in which the skin thickens and darkens in places.

Achondroplasia is a genetic disorder that interferes with bone growth and causes dwarfism (short stature).

Infant acne is common in babies, and usually goes away on its own without treatment or scarring.

See: Kawasaki Disease.

Acute lymphoblastic leukemia is a form of cancer that causes the body to make too many lymphoblasts, a type of white blood cell.

Learn about different types of leukemia and cancers that affect the blood and bone marrow.

Adenoviruses are a group of viruses that can infect the membranes (tissue linings) of the respiratory tract, eyes, intestines, and urinary tract. They are common among infants and young children.

Adrenal insufficiency is a condition that happens when the adrenal glands do not work properly.

Learn about intestinal blockages and conditions that affect the digestive tract.

Learn about alcohol abuse and consequences of excessive drinking.

With allergies, the immune system overreacts and tries to "fight" allergens, which are ordinary things that cause an allergic reaction.

Normally medicines help us treat disease, but in people with drug allergies, taking certain medicines can cause the immune system to react and harm the body.

Alopecia areata is a condition that causes hair loss on the scalp and sometimes elsewhere on the body.

Learn about genetic disorders and diseases and conditions that affect the blood.

Amebiasis is an intestinal illness. People get it after eating, drinking, or touching something that's contaminated with a tiny parasite called Entamoeba histolytica.

Amenorrhea is when a girl is not getting her period.

Primary amenorrhea is when a girl does not start her period by age 15 or 3 years after she begins puberty.

Secondary amenorrhea is when a girl who had been getting her period stops menstruating for more than 6 months or for more than three of her usual cycles.

An anal fissure is a cut or tear in the lining of the anus.

Anaphylaxis is a sudden, life-threatening reaction that is usually caused by an allergy.

Learn about anemia, a common blood disorder that happens when the level of healthy red blood cells in the body becomes too low.

Learn about anorexia nervosa, a type of eating disorder.

Learn more about ACL injuries and how they're treated.

Appendicitis is an inflammation of the appendix, and requires surgery.

Apthous ulcers, or canker sores, are non-contagious small ulcers that can occur inside the mouth, often causing discomfort during eating or talking.

An arrhythmia is an abnormal heart rhythm usually caused by an electrical "short circuit" in the heart.

In this condition, an abnormal connection between arteries and veins causes blood to flow too quickly, leading to a risk of bleeding. Learn more here.

Learn about conditions that affect the heart and blood vessels.

Learn about congenital conditions and conditions that affect the muscles and joints in newborn babies.

Learn about conditions that affect the joints, complications of diabetes, and complications of nervous system damage.

Asthma is a lung condition that causes difficulty breathing.

Learn more about asthma attacks, when asthma symptoms suddenly become severe.

People with this type of asthma have a cough but no wheezing. Learn more about it here.

This type of brain tumor involves star-shaped cells of the brain that grow out of control. Learn about it here.

Learn about this genetic disorder that can weaken the immune system and cause gradual worsening of balance, coordination, and speech.

See: Cerebellar Ataxia.

See: Eczema.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Atrial flutter is an abnormal heart rhythm that causes the heart to beat too fast.

Learn about congenital heart defects and conditions that affect the heart and circulatory system.

Learn about congenital heart defects and conditions that affect newborn babies.

Learn about behavioral disorders and conditions that affect children's moods, activities, and interactions.

Learn about developmental disorders and conditions that affect children's moods, activities, and interactions.

In aortic stenosis, the aortic valve is narrower than it's supposed to be and can't open all the way.

An asthma action plan is a set of individualized written instructions, designed with a doctor, that detail how a person with asthma should manage his or her asthma at home.

Back pain is fairly common, and is often due to muscle strain or sprain. In students, wearing a heavy backpack is a common cause.

Learn about parasitic infections, tickborne illnesses, and conditions that affect the bloodstream and red blood cells.

Bacterial vaginosis (BV) is an infection in the vagina.

Learn about conditions that affect the penis and foreskin.

Learn more about this inflammation of the foreskin and head of the penis.

Learn about complications of acid reflux and conditions that affect the esophagus and upper gastrointestinal tract.

Learn about complications of viral infections and conditions that can affect the face and nervous system.

Learn about inherited disorders and conditions that can affect the joints and connective tissues.

Learn about complications of poor nutrition and conditions that can affect the cardiovascular and nervous systems.

Learn about genetic disorders and diseases and conditions that affect the blood.

Learn more about biceps tendonitis and how it's treated.

Learn about depressive disorders, mental illnesses, and conditions that affect moods and the brain.

Learn about the causes of eye irritation and conditions that can affect the eyes and eyelids.

After a burn or excessive pressure to the skin, a fluid-filled pocket in the skin can form and cause pain and irritation. Learn more here.

Blood in the stool means the presence of blood in a bowel movement.

See: Hematuria (Blood in Urine).

Learn about mental health disorders and causes of low self-esteem and negative thoughts about body image.

Learn about personality disorders and complications of mental illness.

Learn about bacterial infections, foodborne illnesses, and conditions that affect the nervous system.

Learn about bacterial infections, foodborne illnesses, and conditions that affect the nervous system.

Learn about bacterial infections, foodborne illnesses, and conditions that affect the nervous system.

Learn about bacterial infections, foodborne illnesses, and conditions that affect the nervous system.

Learn more about this type of noncancerous tumor, common in women ages 15-35.

Learn about causes of breathing difficulties and conditions that can affect the lungs and bronchi.

See: Bronchiectasis.

See: Bronchiectasis.

Bronchiolitis is a common illness of the respiratory tract caused by an infection that affects the bronchioles, tiny airways that lead to the lungs.

Bronchitis (say: bron-kye-tis) is an inflammation of the lining of the bronchial tubes, the airways that connect the trachea (windpipe) to the lungs.

Bruxism is the medical term for grinding the teeth or clenching the jaws.

Learn about eating disorders and complications of negative thoughts about eating, food, and body image.

Learn about bullous myringitis, an infection of the tympanic membrane (eardrum).

A first-degree burn is a minor burn that only affects the top layer of skin, or epidermis. It is the mildest of the three types of burns (first-degree, second-degree, and third-degree).

A second-degree burn affects the top two layers of skin (the epidermis and dermis). It is more serious than a first-degree burn.

Third-degree burns, or full-thickness burns, are the most serious type of burn. They involve all the layers of the skin and underlying tissue and can cause permanent damage.

Most causes of chest pain in kids and teens are not serious and will clear up with minimal or no treatment.

Coughing is a symptom, not a disease, and sometimes can help clear the airway.

Babies use crying to communicate, and during the first 3 months of life, they cry a lot. Knowing what to expect can help parents and caregivers manage.

See: Sever Disease.

Candidiasis is an overgrowth of a type of yeast, and commonly causes infections in the mouth, vagina, and skin.

See Apthous Ulcers (Canker Sores).

With this medical emergency, the heart suddenly stops beating and prevents oxygen from getting to the body. Read more about it here.

Diseases can put added strain on the heart. As it enlarges to pump more blood to the body, the heart muscle weakens and does not work well in this condition. Read more here.

Learn about cardiomyopathy, a disease in which the heart muscle becomes weak and enlarged, making it difficult to pump blood through the body.

Cat scratch disease is an infection caused by the bacterium Bartonella henselae. It comes from a scratch or bite of an infected cat, usually a kitten.

Learn more about cellulitis, an infection of the skin and underlying tissues.

Learn about orbital cellulitis, a dangerous infection affecting the eye and its surrounding tissue and skin.

A central line — a tube surgically placed into a blood vessel — can be a convenient way to receive medicine through a vein over a long period of time, but it carries the risk of infection.

Learn more about this condition, in which abnormal brain signals cause a person's breathing to stop and start repeatedly during sleep.

Learn about cerebellar ataxia, the loss of muscle coordination caused by disease or injury to the cerebellum.

Cerebral palsy (CP) is a brain disorder that affects muscle tone and motor skills (the ability to coordinate body movements).

Learn about causes of neck pain and conditions that can affect the cervical spine.

A chalazion is a lump on the inner side of the eyelid. It occurs when one of the small oil glands becomes blocked.

Learn about neurological disorders and conditions that affect the arms and legs.

Learn more about infections and problems of the liver and biliary tract.

Learn about cholelithiasis, the presence of gallstones (hard, pebble-like objects made of bile).

Learn about genetic disorders and conditions that affect growth and development.

Learn about bilateral cleft lip, a common birth defect in which a baby's lip doesn't form properly, resulting in splits (clefts) on both sides of the lip.

Learn about unilateral cleft lip, a common birth defect in which a baby's lip doesn't form properly, resulting in a split (cleft) on one side of the lip.

A cleft palate with a bilateral cleft lip is a common birth defect in which a baby's lip and palate (roof of mouth) don't form properly. As a result there is a split or opening (cleft) on both sides of the lip that can extend all the way from the nose to the back of the palate.

A cleft palate with a unilateral cleft lip is a common birth defect in which a baby's lip and palate (roof of mouth) don't form properly. As a result there is a split or opening (cleft) on one side of the lip that can extend all the way from the nose to the back of the palate.

Clubfoot is a birth defect that causes one or both of a baby's feet to turn inward and downward, giving the foot or feet a club-like appearance.

Learn about coarctation of the aorta, a treatable congenital heart defect in which a person's aorta is narrowed at some point.

Colic is defined as crying for more than 3 hours a day, for more than 3 days a week, for at least 3 weeks.

Learn about inflammatory disorders and conditions that affect the intestines and digestive system.

Learn about this common disorder that lowers the amount of antibodies a person's body can make and limits the ability to fight infections.

In this condition that starts in the womb, reversed connections of the aorta and pulmonary artery prevent the blood from getting oxygen. Learn more here.

It is important to carefully monitor and treat this potential complication of head injuries and diseases affecting the brain. Read about it here.

A concussion is a brain injury that causes temporary changes in the way the brain works. It's usually a result of impact or a blow to the head.

Sometimes babies are born with anomalies - one or more parts of the body that are different from normal in size, shape, or functioning. Learn more here.

In this condition, which can affect a child's breathing, activity, and growth, the heart is unable to pump blood efficiently and meet the needs of the body.

Conjunctivitis is an inflammation of the conjunctiva, the tissue covering the white part of the eye and the inner surface of the eyelid.

Constipation -- having fewer and harder bowel movements (poops) than usual -- is rarely due to a serious condition.

Contracture of tendon sheath is a rare condition where the protective sheath surrounding a tendon tightens and grows thicker, which can limit movement in an affected joint.

Learn more about contusions (bruises) of the abdomen.

Learn more about ankle contusions (bruises).

Learn more about contusions (bruises) of the back.

Learn more about contusions (bruises) of the buttocks.

Learn more about contusions (bruises) of the chest.

Learn more about elbow contusions (bruises).

Learn more about black eyes and contusions (bruises) of the eye.

Learn more about black eyes and eyelid contusions in children.

Learn about contusions (bruises) of the face, scalp, and neck.

Learn more about contusions (bruises) of the finger.

Learn more about contusions (bruises) of the forearm.

Learn more about contusions (bruises) of the hand.

Learn more about contusions (bruises) of the hip.

Learn more about contusions (bruises) of the knee.

Learn more about contusions (bruises) of the lower leg.

Learn more about contusions (bruises) of the shoulder.

This common viral infection can affect the respiratory tract. Almost everyone has had it at some point in their life. Learn about coronavirus here.

Costochondritis is an inflammation of the cartilage that attaches a rib to the breastbone (sternum).

A to Z: Coxa Valga

Learn about coxsackieviruses, part of the enterovirus family of viruses that live in the human digestive tract.

Learn about craniopharyngioma, a treatable type of brain tumor that can affect a person's vision, growth, and development.

Crohn's disease causes problems in the intestine (bowel) that can prevent the bowel from digesting food well.

Croup is a viral infection that causes an inflammation of the upper airways — the voice box (larynx) and windpipe (trachea).

Cryptorchidism is a condition in which one or both of a boy's testicles (testes) have not moved into their proper place in the scrotum.

A cerebral cyst is a sac filled with fluid, and sometimes other materials, that develops in or around the brain.

A meibomian cyst, or chalazion, is a lump on the inner side of the eyelid. It occurs when one of the small oil glands becomes blocked.

Learn about complications of ovulation and conditions that affect the female reproductive system.

Learn about cystic fibrosis, an inherited disease primarily affecting the lungs and digestive system.

Learn about cystitis (inflammation of the bladder, commonly called a bladder infection). It is the most common type of urinary tract infection (UTI).

Learn about viral infections and conditions that can affect pregnancy, newborn babies, and people with weakened immune systems.

See: Hashimoto's Thyroiditis.

Cough is a common symptom in people who have asthma, although it can occur for many other reasons.

Most causes of chest pain in kids and teens are not serious and will clear up with minimal or no treatment.

See: Kawasaki Disease.

An arrhythmia is an abnormal heart rhythm usually caused by an electrical "short circuit" in the heart.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Learn about congenital defects and conditions that affect vessels, valves, and passages in the heart and other organs.

Atrial flutter is an abnormal heart rhythm that causes the heart to beat too fast.

Learn about congenital heart defects and conditions that affect the heart and circulatory system.

Learn about congenital heart defects and conditions that affect newborn babies.

With this medical emergency, the heart suddenly stops beating and prevents oxygen from getting to the body. Read more about it here.

Diseases can put added strain on the heart. As it enlarges to pump more blood to the body, the heart muscle weakens and does not work well in this condition. Read more here.

Learn about cardiomyopathy, a disease in which the heart muscle becomes weak and enlarged, making it difficult to pump blood through the body.

Learn about coarctation of the aorta, a treatable congenital heart defect in which a person's aorta is narrowed at some point.

In this condition that starts in the womb, reversed connections of the aorta and pulmonary artery prevent the blood from getting oxygen. Learn more here.

Learn more about dysrhythmia: an abnormality in the heart's beat or rhythm caused by electrical impulses functioning improperly.

Learn about Ebstein's anomaly, a rare defect in the right side of the heart that is present at birth (congenital).

Learn about congenital heart defects and conditions that affect newborn babies.

Learn about types of high blood pressure and conditions that can affect the heart and blood vessels.

Learn about types of high blood pressure and conditions that can affect the lungs and heart.

Learn about hypoplastic left heart syndrome, a rare and serious defect of the heart.

Read about this condition in which the aorta has developed in a way that divides it into two parts and interrupts the proper flow of blood.

Learn about Kawasaki disease, an illness that involves the skin, mouth, and lymph nodes.

Learn about arrhythmias and conditions that affect the heart and heartbeat.

Paroxysmal supraventricular tachycardia (PSVT) is a type of arrhythmia in which the heart beats very rapidly.

Learn about heart conditions that affect newborn and premature babies.

Learn about complications of infections and conditions that affect the heart.

Learn about this congenital heart defect that alters blood flow through the heart and lungs and can affect a child's growth and circulation.

Learn more about types of arrhythmias and problems of the heart.

Learn about tetralogy of Fallot, a rare congenital heart disorder.

In the womb, a child's heart may develop a single large artery rather than separate aortic and pulmonary arteries. Learn about the condition here.

Learn about congenital heart defects and conditions that affect the heart and circulatory system.

Learn about ventricular tachycardia, a potentially life-threatening arrhythmia in which the heart beats too rapidly.

Learn about Wolff-Parkinson-White Syndrome, a congenital heart condition that can cause an abnormally fast heart rhythm known as supraventricular tachycardia.

In aortic stenosis, the aortic valve is narrower than it's supposed to be and can't open all the way.

Diarrhea (loose, watery, or more frequent stools) can be a symptom of many conditions, including common infections. Most cases go away in a few days with proper home care.

Dizziness refers to feelings of lightheadedness, imbalance, or vertigo (the sensation that one’s surroundings are spinning or moving).

Learn about complications of injuries and illnesses and conditions that affect the size and shape of body parts.

Learn about types of birth defects and conditions that affect the size and shape of body parts.

Learn about dehydration, a condition that occurs when someone loses more fluids than he or she takes in.

A dental cavity is a hole in the tooth that can grow bigger and deeper over time.

Depression is a mood disorder that can affect people of all ages, including kids and teens.

Learn about dermatitis, inflammation of the skin that causes itching and discomfort.

Learn about atopic dermatitis, an inflammation of the skin that causes itching and discomfort.

Learn about contact dermatitis, inflammation of the skin that causes itching and discomfort.

Learn about dermatitis, inflammation of the skin that causes itching and discomfort.

Learn about seborrheic dermatitis, inflammation of the skin that causes itching and discomfort.

Learn about dermatomyositis, an inflammatory muscle disease that weakens muscles and produces a distinctive skin rash.

Dermatophytosis, or ringworm, is a highly contagious infection of the skin, hair, or nails caused by a type of fungus called a dermatophyte.

As kids grow they develop socially and emotionally, and they learn speech, language, motor skills, and cognitive thinking. But in some kids that development can be delayed. Learn more here.

In this condition, dislocation of the hip joint around the time of birth can affect a child's growth, development, and movement.

Diabetes is a disease that affects the way the body handles glucose, a sugar released by the foods we eat.

In central diabetes insipidus, the kidneys make large amounts of urine, causing the body to lose too much water.

In nephrogenic diabetes insipidus, the body loses too much water because of a problem with the kidneys.

Diabetes is a disease that affects how the body uses glucose. In type 1 diabetes, the pancreas doesn't make enough insulin, a chemical in the body that helps glucose enter the cells.

Diabetes is a disease that affects how the body uses glucose. In type 2 diabetes, the body can't respond normally to insulin, a hormone that helps glucose enter the cells.

Diabetic ketoacidosis (DKA) can be a life-threatening complication of uncontrolled diabetes.

Diastrophic dysplasia is a rare genetic disorder that interferes with bone development and causes abnormal bone growth and dwarfism (short stature).

Learn about conditions that affect the brain, central nervous system, and muscle coordination.

A dislocation is when the bones in a joint slip out of their normal position. A dislocated elbow happesn when the upper and lower parts of the arm to slip out of position.

A dislocation is when the bones in a joint slip out of their normal position. A finger dislocation may happen from a fall, blow, or sports injury, especially if the finger is bent back or jammed.

A dislocation is when the bones in a joint slip out of their normal position. A hip dislocation is an injury that occurs when the ball of the thighbone moves out of the socket of the hipbone.

A shoulder dislocation causes the top of the upper arm bone (humerus) to slip out of its normal position in the shoulder socket.

A dislocation is when the bones in a joint slip out of their normal position. A dislocated thumb may happen from a fall, blow, or sports injury, especially if the thumb is bent back or jammed.

A dislocation is when the bones in a joint slip out of their normal position. A dislocated toe may happen from a blow or jamming the toe, such as bumping the toe into furniture or during sports.

See: Osteoporosis, Disuse.

Learn about Down syndrome (DS), a condition in which extra genetic material causes delays in the way a child develops, both mentally and physically.

Newborn babies who were exposed to drugs or alcohol while in the womb can develop this syndrome after birth. Learn about it here.

Learn more about diseases and conditions of the stomach and digestive system.

"Dysmenorrhea" means difficult or painful periods.

Swallowing difficulties can affect many aspects of a child's health, including feeding, breathing, and overall growth.

Learn more about difficult or labored breathing.

Learn more about dysrhythmia: an abnormality in the heart's beat or rhythm caused by electrical impulses functioning improperly.

Learn more about dysuria (or painful urination) and its treatment.

DNA is the genetic information inside the cells of the body that helps make people who they are.

A perforated (or ruptured) eardrum is a hole in the eardrum caused by injury or infection.

Eating disorders involve self-critical, negative thoughts and feelings about body weight and food, and eating habits that disrupt normal body function and daily activities.

Learn about Ebstein's anomaly, a rare defect in the right side of the heart that is present at birth (congenital).

The kidneys and urinary tract (which includes the ureters) filter and eliminate wastes from the blood. But sometimes a ureter doesn't connect to the bladder in the usual place, a condition known as an ectopic ureter.

Learn about genetic conditions, allergic reactions, and conditions that can affect the skin.

Eczema herpeticum is a skin infection that occurs when the skin becomes infected by herpes simplex (the type of viruses that causes cold sores).

Learn about edema, swelling due to the build-up of excess fluid in body tissues.

Learn about encephalopathy, a broad term used to describe brain dysfunction.

See: Chondrodystrophy.

Encopresis (soiling) is a condition that causes a child beyond the age of toilet training to have bowel movements (poop) in his or her underwear.

Learn about congenital heart defects and conditions that affect newborn babies.

Learn about congenital heart defects and conditions that affect newborn babies.

Learn about complications of infections and conditions that affect the female reproductive system.

See: Hypertrophy, Tonsillar.

Learn more about this common complication of infections and conditions that can affect the small intestine and digestive system.

Enterovirus infections can affect the digestive tract, skin, and respiratory and central nervous systems.

Learn about rheumatic disorders and conditions that affect the joints and entheses.

Enuresis (bedwetting) is a condition where a person has trouble controlling his or her urination (pee).

Learn about allergic reactions and diseases of the esophagus and gastrointestinal tract.

This tumor forms from cells in the brain and spinal cord that make cerebrospinal fluid. Learn more about this cancer here.

Epididymitis refers to swelling and inflammation of the epididymis, the coiled tube at the back of the testicle that holds and carries sperm.

Epilepsy is a seizure disorder in which electrical signals in the brain misfire, causing temporary communication problems between nerve cells. Someone who gets recurrent seizures is thought to have epilepsy.

Epistaxis is another word for nosebleed, when small blood vessels break in the tissue lining of the nose.

Erythema multiforme is a skin condition caused by a hypersensitive reaction to an infection or, in some cases, medication.

Learn about conditions that affect the esophagus and upper gastrointestinal tract.

This type of speech problem can make it hard for kids to put words together and express what they want to say. Learn more here.

In most cases, fainting is not a sign of a dangerous problem, but should still be discussed with a doctor.

A fever itself is a symptom, causes no harm, and is often the body's way of fighting infections.

In factor IX deficiency (hemophilia B), the body doesn't make enough factor IX (factor 9), one of the substances the body needs to form a clot.

In factor VIII deficiency (hemophilia A), the body doesn't make enough factor VIII (factor 8), one of the substances the body needs to form a clot.

Failure to thrive refers to a child's inability to gain weight and grow as expected for kids of the same age and gender. Most diagnoses are made in the first few years of life.

Febrile seizures are convulsions that can happen during a fever (febrile means "feverish").

Some babies refuse to eat or don't eat enough. Others have problems digesting food. Learn more about common feeding problems here.

See: Pilonidal Cyst.

Flat foot is a condition in which the arches on the inside of a person's foot have less curve to them or are flat, so that the entire sole of the foot rests on the ground when the person is standing.

It may seem embarrassing to talk about, but intestinal gas and the sounds and smells it causes are common and usually totally normal. Learn more here.

Learn more about influenza, a highly contagious viral infection of the respiratory tract.

Food poisoning happens when bacteria (and, sometimes, viruses or other germs) get into food or drinks.

Having a foreign object in the ear is a common cause for a visit to the emergency room, especially for kids under age 6.

To prevent damage to the eye, any object that isn't washed out right away by tears must be removed.

Having an object (or foreign body) in the nose is a common cause for a visit to the emergency room, especially for kids under age 6.

Learn about types of lower extremity fractures and conditions that can affect the ankle and lower leg.

A clavicle fracture, or broken collarbone, is one of the most common broken bones among kids and teens.

A fall onto the shoulder or an outstretched arm can result in this type of broken bone. Learn more here.

Fractures of the distal radius and ulna, or broken bones of the forearm, are common childhood injuries.

Fractured (broken) elbows are a common injury in kids and teens.

A fractured fibula is a break to the smaller of the two bones in the lower leg.

Learn about types of lower extremity fractures and conditions that can affect the ankle and lower leg.

Sports injuries or blows to the face can often cause this common type of facial injury. Learn about it here.

A fractured radius is a broken bone in the lower arm. It is a common injury that usually heals quickly.

A fractured scaphoid is a broken small bone in the wrist.

A skull fracture is a break or crack in one of the bones of the skull, also called the cranium.

Kids with this inherited disorder can do well with therapies to help treat the intellectual, emotional, and behavioral challenges they face. Learn more here.

A fractured patella is a broken kneecap (the flat, round bone that protects the knee joint).

This type of brain tumor forms in the brain stem, the part of the brain that coordinates messages and controls processes like breathing and digestion. Learn more here.

Learn about abnormality of gait (or gait abnormality), an unusual walking pattern or style.

Galactosemia is an inherited disorder in which the body can't break down a type of sugar called galactose.

See: Cholelithiasis.

Learn more about diseases and conditions of the stomach and digestive system.

Gastroenteritis is an infection that causes vomiting and diarrhea.

Learn more about diseases and conditions of the stomach and digestive system.

Learn more about this problem of the stomach and digestive tract.

Learn about gastroschisis, a type of hernia that some babies are born with.

Learn about common childhood orthopedic conditions and conditions that affect the legs and knees.

Learn about common childhood orthopedic conditions and conditions that affect the legs and knees.

Gestational diabetes is a kind of diabetes that happens to pregnant women. Most of the time, it goes away after the mom has her baby.

Giardiasis is an illness of the digestive tract (stomach and intestines).

Herpetic gingivostomatitis is a contagious mouth infection caused by herpes simplex virus type 1 (HSV-1). It most often occurs in young children and is usually the first exposure a child has to the herpes virus (which is also responsible for cold sores and fever blisters).

Glomerulonephritis is an inflammation of the glomeruli, the parts of the filtering units (nephrons) of the kidney.

Glycogenosis is a broad term for 11 different disorders that cause the abnormal use and storage of glycogen in the body's tissues.

When a person receives a stem cell transplant, this treatable complication can make it tougher for the immune system to heal.

Learn about granulomatosis with polyangiitis (GPA), an uncommon autoimmune disorder that causes inflammation of the blood vessels.

Graves disease is a condition where the body's immune system causes the thyroid gland to make more thyroid hormones than it should.

Growth disorders are medical problems that stop kids from growing taller or gaining weight as they should.

Headaches are common in kids and teens, and can have a wide range of causes. Most can be managed at home.

Hand, Foot, and Mouth disease is a common contagious illness caused by viruses from the enterovirus family, most commonly the coxsackievirus.

Hashimoto's thyroiditis is a chronic (ongoing) condition where the body's immune system attacks the thyroid, a gland in the neck that makes thyroid hormone.

See: Rhinitis, Allergic.

Learn more about head injuries (head trauma).

Learn about causes of hearing loss and conditions that can affect the outer ear and middle ear.

Learn about causes of hearing loss and conditions that can affect the ear and auditory nerve.

Learn about causes of hearing loss and conditions that can affect the auditory nerve.

See: Hearing Loss, Sensorineural.

Learn about causes of hearing loss and conditions that can affect the inner ear and auditory nerve.

Learn more about hemangiomas, common birthmarks in infants.

Learn more about diseases and conditions of the stomach and digestive system.

Learn more about hematuria (blood in urine) and how it's treated.

Learn about congenital disorders and conditions that affect the brain and central nervous system.

Hemophagocytic syndrome (HPS) is a rare and potentially life-threatening blood disorder of the immune system. It mostly affects infants and children but can develop at any age.

In factor VIII deficiency (hemophilia A), the body doesn't make enough factor VIII (factor 8), one of the substances the body needs to form a clot.

In hemophilia B (factor IX deficiency), the body doesn't make enough factor IX (factor 9), one of the substances the body needs to form a clot.

Learn about causes of stroke and conditions that can affect the brain.

This condition happens when a blood vessel on the surface of the eye breaks open and leaves a red spot on the white of the eye. Learn more here.

Learn about Henoch-Schönlein purpura, a condition in which capillaries in the skin, kidneys, and intestinal tract become inflamed and leak.

In this inherited condition, people can have attacks of swelling in the skin, airways, and intestines. Learn about hereditary angioedema here.

A bilateral hernia is an opening or weakness in the abdominal wall on both sides of the groin. Learn about it here.

Learn about hernias and conditions that affect the abdomen and abdominal muscles.

Learn about hernias and conditions that affect the stomach, esophagus, and upper gastrointestinal tract.

Learn about hernias and potential complications of abdominal surgery.

Learn about hernias and conditions that affect the lower abdomen and reproductive organs.

Learn about hernias and conditions that affect the abdomen and bellybutton.

Learn more about viral infections and conditions that affect the mouth and throat.

Learn about viral infections, types of herpes, and conditions that affect the mouth and face.

Learn about viral infections, types of herpes, and conditions that affect the genital area.

Learn about viral infections and causes of skin conditions.

In this condition, which often begins during the teen years, lumps form under the skin in areas like the armpit or groin. Learn more here.

Learn about Hirschsprung disease, a birth defect that prevents a child from passing bowel movements.

Learn about urticaria, the red raised bumps or welts on the skin that are commonly called hives.

See: Mucopolysaccharidosis (Hunter Syndrome).

A hydrocele is a collection of fluid around the testicle within the scrotum.

Hydrocephalus (sometimes called "water on the brain") is a brain condition that happens when cerebral spinal fluid (CSF) is unable to drain from the brain.

Learn about the central nervous system and conditions that can affect the spinal cord.

Learn more about hydronephrosis (swollen kidney) in children.

Learn more about diseases and conditions of the blood and kidneys.

Hyperopia is farsightedness, a common condition in which someone can see things in the distance clearly, but things that are closer appear blurry.

Learn about causes of vision loss and conditions that can affect the brain and nervous system.

Learn about types of high blood pressure and conditions that can affect the heart and blood vessels.

Learn about types of high blood pressure and conditions that can affect the lungs and heart.

In this common condition, there is a high level of fats called triglycerides in the blood. Learn how this is related to diet, lifestyle, and heart disease here.

Tonsillar hypertrophy, or enlarged tonsils, can happen due to an ongoing (chronic) condition or a temporary effect of an infection.

Hyphema is a condition that happens when blood collects in the front part of the eye.

Learn about complications of white blood cell deficiencies and conditions that affect the immune system.

Learn more about hypoglycemia, a condition where glucose levels drop below normal.

Hyponatremia is an abnormally low level of sodium in the blood.

Learn about hypoplastic left heart syndrome, a rare and serious defect of the heart.

Learn about metabolic conditions and conditions that can affect fluid and electrolyte levels in the blood.

Hypospadias is a birth defect in which the tube that carries urine out of the body, called the urethra, opens on the underside of the penis.

Hypothermia is a medical emergency resulting from dangerously low body temperature.

Hypothyroidism is when the thyroid gland doesn't send enough thyroid hormone into the blood.

Hypoxemia is a condition in which there is a lower than normal level of oxygen in the blood.

Learn about immune system responses and conditions that can affect the blood.

Learn about intestinal blockages and conditions that affect the digestive tract.

See: Idiopathic Thrombocytopenic Purpura.

Learn more about imnpacted earwax build-up, which can cause temporary hearing loss and ear pain.

Impetigo is a contagious skin infection caused by bacteria.

A skin infection is a condition where bacteria or other germs enter the skin through a wound and spread, causing pain, swelling, and discoloration.

Inflammatory bowel disease is a term medical people use for two diseases of the intestines, Crohn's disease and ulcerative colitis, that cause problems in the intestine.

Learn more about influenza (the flu), a highly contagious viral infection of the respiratory tract.

Bites from non-venomous insects are the result of an insect attempting to feed upon a person's blood. Non-venomous means the insect does not inject poisons through its bite.

Venomous insects bite or sting people as a way to defend themselves. They inject a poison (venom) into a person through their mouth or stinger which causes a reaction.

Read about this condition in which the aorta has developed in a way that divides it into two parts and interrupts the proper flow of blood.

Learn about congenital heart defects and conditions that affect the heart and circulatory system.

Learn about gastrointestinal problems and conditions that affect the digestive system.

Malrotation is twisting of the bowel that happens when a baby's intestines don't develop properly in the uterus. It can be a medical emergency.

See: Hemorrhage, Intracerebral.

Intussusception is a problem with the intestine in which one portion of the bowel slides into the next.

Learn more about conditions of the eyes and factors that may contribute to vision loss.

Learn more about conditions of the eyes and factors that may contribute to vision loss.

Iron-deficiency anemia occurs when there aren't enough healthy red blood cells in the bloodstream to carry oxygen to the body's tissues.

Irritable bowel syndrome (IBS) is a common intestinal disorder that can cause cramps, gas, bloating, diarrhea, and constipation. It is sometimes called a "nervous stomach" or a "spastic colon."

Learn about jaundice, when the skin and whites of the eyes appear yellow due to excess bilirubin in the blood.

Learn more about this type of joint swelling that can caused by infections, injuries, and arthritis.

Learn about juvenile idiopathic arthritis, which usually occurs in kids and teens under age 17.

Kids and teens with juvenile myoclonic epilepsy (JME) have multiple seizures that usually start around puberty and continue into adulthood unless the seizures are controlled by medicine.

See: Juvenile Idiopathic Arthritis (JIA).

Learn about Kawasaki disease, an illness that involves the skin, mouth, and lymph nodes.

Learn about complications of wound healing and conditions that affect the skin.

Kidney disease is when there's a problem with the kidneys and they can't do a good job of filtering waste.

When the kidneys stop working, they can't help the body remove waste. Learn more about this condition and how doctors treat it.

Learn more about diseases and conditions of the blood and kidneys.

Learn about this rare disorder that primarily affects adolescent males.

Learn about genetic disorders and conditions that can affect social and sexual development.

Kohler's disease is a rare cause of foot pain that develops from temporary changes in bones in the feet as kids grow.

Learn more about kyphosis, an abnormal rounding of the spine.

Learn more about congenital kyphosis, an abnormal rounding of the spine that develops before birth.

Learn more about postural kyphosis, an abnormal rounding of the spine caused by irregular development of bones and muscles, sometimes due to slouching or poor posture.

Learn more about Scheuermann's kyphosis, an abnormal rounding of the spine that can run in families and is usually seen in teens.

Lactose intolerance happens because the body has trouble digesting a kind of sugar that's in milk products.

See: Fracture, Lateral Malleolus.

Learn about this rare hip disorder, which is most common in boys.

This genetic condition makes a person more likely to get cancer during his or her lifetime. Learn more here.

A lipoma is a non-cancerous mass of fat cells that grows under the skin.

Learn about causes of back pain and conditions that affect the back and spine.

Lyme disease is a bacterial infection spread through the bite of deer ticks.

Learn about bacterial infections and problems of the lymphatic system.

Learn about congenital defects and conditions that affect the lymphatic system.

Malaise and fatigue are common symptoms of many ailments.

Marcus Gunn syndrome is a congenital condition where a drooping eyelid briefly opens wider and appears to wink when the jaw is moved.

The meatus is the opening in the penis where urine (pee) comes out. In meatal stenosis, the meatus is too small.

Learn more about MCL injuries and how they're treated.

A meibomian cyst, or chalazion, is a lump on the inner side of the eyelid. It occurs when one of the small oil glands becomes blocked.

Learn about this rare but serious condition in which bacteria invade the membranes around the brain and spinal cord.

Sometimes viruses can spread to the meninges, the membrane around the brain and spinal cord, and cause more severe illness. Learn about it here.

Learn about types of mental disorders and conditions that affect thinking and behavior.

Metabolic syndrome is a group of separate health problems that often happen together in a person.

Microcephaly is a rare condition in which a child's brain doesn't fully develop, resulting in an abnormally small head size.

A migraine is a recurring headache that often causes nausea, dizziness, and sensitivity to light, sound, or smell.

A migraine without aura is a migraine headache that happens without previous warning signs (auras).

Mitochondrial disorders affect the function of mitochondria, tiny structures within the body's cells that turn sugar and oxygen into the energy the cells need to do their jobs.

Molluscum contagiosum is a common wart-like viral skin infection that goes away on its own over time.

Learn about complications of neurologic disorders and conditions that can affect the peripheral nerves.

Learn more about mononucleosis, an infection caused by the Epstein-Barr virus (EBV) with flu-like symptoms.

Learn about causes and complications of skin infections.

Mucopolysaccharidosis type II, or Hunter syndrome, is a rare genetic disorder that affects mostly males.

Learn about about multiple sclerosis (MS), a chronic disease affecting the central nervous system.

Learn about causes of muscle pain and conditions that affect muscles and muscle groups.

Learn about myasthenia gravis, an autoimmune disease that causes weakness in the voluntary muscles.

Learn about birth defects and conditions that affect the spinal cord and spinal column.

Learn more about the central nervous system and symptoms of nervous system disorders.

Myopia is nearsightedness, a common condition in which someone can see things that are close clearly, but things that are farther away appear blurry.

Learn about causes of muscle weakness and conditions that affect muscles and muscle tissue.

Learn about bullous myringitis, an infection of the tympanic membrane (eardrum).

Learn about bullous myringitis, an infection of the tympanic membrane (eardrum).

Learn about causes and complications of skin infections.

Nausea (stomach upset or feeling queasy) can be caused by many things. Often, it can be managed at home with treatment to prevent dehydration.

Necrotizing enterocolitis (NEC) is a serious intestinal problem where tissue in a newborn's colon dies off. Babies with necrotizing enterocolitis need medical care right away.

See: Granulomatosis With Polyangiitis (GPA).

Learn about tumors and cancer.

Learn about conditions that affect the kidneys and urinary tract.

Learn more about neurofibromatosis (NF), which can cause tumors to grow, including how it's treated.

The term neurogenic bladder refers to a bladder that doesn't function properly because of nervous damage.

See: Mental Disorder, Non-psychotic.

Neutropenia is when the body has very low levels of certain white blood cells called neutrophils, the body's main defense against infection.

In this condition, a broken bone does not heal completely and needs advanced treatment. Learn more.

Learn about viral infections and conditions that affect the stomach and digestive system.

Nursemaid's elbow is a common injury in young kids that happens when a ligament slips out of place near the elbow.

Learn more about this eye problem.

Learn about causes and complications of obesity and morbid obesity.

See: Obesity, Morbid.

Learn about this common sleep disorder, where a blockage of the airway during sleep can cause someone to temporarily stop breathing.

See: Chondrodystrophy.

Learn about bacterial infections and conditions that affect newborn babies.

Learn more about cheek wounds and how they're treated.

Learn about ear wounds and how they're treated.

Learn more about elbow wounds and how they're treated.

Learn about face wounds and how they're treated.

Learn more about finger wounds and how they're treated.

Learn more about foot wounds and how they're treated.

Learn more about forearm wounds and how they're treated.

Learn more about forehead wounds and how they're treated.

Learn more about gum wounds and how they're treated.

Learn more about hand wounds and how they're treated.

Learn more about head wounds and how they're treated.

Learn more about wounds of this hip or thigh and how they're treated.

Learn more about jaw wounds and how they're treated.

Learn more about knee, leg, and ankle wounds and how they're treated.

Learn more about lip wounds and how they're treated.

Learn more about mouth wounds and how they're treated.

Learn more about nose wounds and how they're treated.

Learn more about scalp wounds and how they're treated.

Learn more about toe wounds and how they're treated.

Learn more about tongue wounds and how they're treated.

Learn more about wrist wounds and how they're treated.

An optic nerve glioma is a type of brain tumor that forms in or around the optic nerve, which connects the eye to the brain.

See Apthous Ulcers (Canker Sores).

Learn about orthostatic hypotension, an abnormal drop in blood pressure that occurs when someone moves from sitting or lying down to standing up.

Learn about osteochondritis dissecans, a joint condition in which a piece of bone and cartilage become unattached, either partially or completely.

Learn about complications of kidney and liver disease and conditions that affect bone development.

See: Osteodystrophy.

Learn more about congenital disorders and bone deformities.

Learn about bacterial infections and conditions that can affect bones.

Mostly affecting older people, osteoporosis is a disease that weakens the bones, causing them to become brittle and easily fractured.

Disuse osteoporosis is bone loss that results from not enough stress or pressure on the bones, making them brittle and weak, and easy to fracture.

Learn about otalgia, more commonly known as ear pain or earache.

Learn more about otitis media, an infection of the middle ear.

Learn more about otorrhea, discharge from the external part of the ear.

Acute lymphoblastic leukemia is a form of cancer that causes the body to make too many lymphoblasts, a type of white blood cell.

Learn about different types of leukemia and cancers that affect the blood and bone marrow.

This type of brain tumor forms in the brain stem, the part of the brain that coordinates messages and controls processes like breathing and digestion. Learn more here.

This tumor forms from cells in the brain and spinal cord that make cerebrospinal fluid. Learn more about this cancer here.

When a person receives a stem cell transplant, this treatable complication can make it tougher for the immune system to heal.

Hemophagocytic syndrome (HPS) is a rare and potentially life-threatening blood disorder of the immune system. It mostly affects infants and children but can develop at any age.

Learn about tumors and cancer.

Neutropenia is when the body has very low levels of certain white blood cells called neutrophils, the body's main defense against infection.

Primitive neuroectodermal tumors, or PNETs, are tumors that can happen anywhere in the brain or spine.

Abnormality of gait (or gait abnormality) is an unusual walking pattern or style.

Achondroplasia is a genetic disorder that interferes with bone growth and causes dwarfism (short stature).

Learn more about ACL injuries and how they're treated.

Learn about congenital conditions and conditions that affect the muscles and joints in newborn babies.

Learn about inherited disorders and conditions that can affect the joints and connective tissues.

Learn more about biceps tendonitis and how it's treated.

See: Sever Disease.

Learn about causes of neck pain and conditions that can affect the cervical spine.

Clubfoot is a birth defect that causes one or both of a baby's feet to turn inward and downward, giving the foot or feet a club-like appearance.

Contracture of tendon sheath is a rare condition where the protective sheath surrounding a tendon tightens and grows thicker, which can limit movement in an affected joint.

In this condition, dislocation of the hip joint around the time of birth can affect a child's growth, development, and movement.

Diastrophic dysplasia is a rare genetic disorder that interferes with bone development and causes abnormal bone growth and dwarfism (short stature).

A dislocation is when the bones in a joint slip out of their normal position. A dislocated elbow happesn when the upper and lower parts of the arm to slip out of position.

A dislocation is when the bones in a joint slip out of their normal position. A finger dislocation may happen from a fall, blow, or sports injury, especially if the finger is bent back or jammed.

A dislocation is when the bones in a joint slip out of their normal position. A hip dislocation is an injury that occurs when the ball of the thighbone moves out of the socket of the hipbone.

A shoulder dislocation causes the top of the upper arm bone (humerus) to slip out of its normal position in the shoulder socket.

A dislocation is when the bones in a joint slip out of their normal position. A dislocated thumb may happen from a fall, blow, or sports injury, especially if the thumb is bent back or jammed.

A dislocation is when the bones in a joint slip out of their normal position. A dislocated toe may happen from a blow or jamming the toe, such as bumping the toe into furniture or during sports.

See: Osteoporosis, Disuse.

See: Chondrodystrophy.

Learn about rheumatic disorders and conditions that affect the joints and entheses.

Learn about types of lower extremity fractures and conditions that can affect the ankle and lower leg.

A clavicle fracture, or broken collarbone, is one of the most common broken bones among kids and teens.

A fall onto the shoulder or an outstretched arm can result in this type of broken bone. Learn more here.

Fractures of the distal radius and ulna, or broken bones of the forearm, are common childhood injuries.

Fractured (broken) elbows are a common injury in kids and teens.

A fractured fibula is a break to the smaller of the two bones in the lower leg.

Learn about types of lower extremity fractures and conditions that can affect the ankle and lower leg.

A fractured radius is a broken bone in the lower arm. It is a common injury that usually heals quickly.

A fractured scaphoid is a broken small bone in the wrist.

Learn about abnormality of gait (or gait abnormality), an unusual walking pattern or style.

Learn about common childhood orthopedic conditions and conditions that affect the legs and knees.

Learn about common childhood orthopedic conditions and conditions that affect the legs and knees.

Learn more about this type of joint swelling that can caused by infections, injuries, and arthritis.

Learn more about kyphosis, an abnormal rounding of the spine.

Learn more about congenital kyphosis, an abnormal rounding of the spine that develops before birth.

Learn more about postural kyphosis, an abnormal rounding of the spine caused by irregular development of bones and muscles, sometimes due to slouching or poor posture.

Learn more about Scheuermann's kyphosis, an abnormal rounding of the spine that can run in families and is usually seen in teens.

See: Fracture, Lateral Malleolus.

Learn about this rare hip disorder, which is most common in boys.

Learn about causes of back pain and conditions that affect the back and spine.

Learn more about MCL injuries and how they're treated.

Nursemaid's elbow is a common injury in young kids that happens when a ligament slips out of place near the elbow.

See: Chondrodystrophy.

Learn about osteochondritis dissecans, a joint condition in which a piece of bone and cartilage become unattached, either partially or completely.

Learn about complications of kidney and liver disease and conditions that affect bone development.

Learn more about congenital disorders and bone deformities.

Mostly affecting older people, osteoporosis is a disease that weakens the bones, causing them to become brittle and easily fractured.

Disuse osteoporosis is bone loss that results from not enough stress or pressure on the bones, making them brittle and weak, and easy to fracture.

Patellar dislocation happens when the patella (kneecap) slips out of its normal position.

Learn more about pectus carinatum, commonly called pigeon chest.

Learn more about pectus excavatum, commonly called sunken chest.

Bimalleolar fracture, Pott's fracture, medial malleolus, lateral malleolus, ankle, ankle fracture, broken ankle, tibia, fibula, shinbone, operative fixation, surgery, malleoli

Learn about scoliosis, an abnormal curvature in the spine often detected just before puberty begins.

Sever disease is a painful bone disorder due to inflammation (swelling) of the growth plate in the heel.

In slipped capital femoral epiphysis (SCFE), the very top of the thighbone (called the femoral head) slips out of line with the rest of the thighbone, causing a weakened hip joint.

Activities and sports that put stress on the back can lead to a slipped disc, which can cause pain in the back, arms, and legs.

Spinal stenosis is a narrowing of the spaces in the spine, or backbone, where the spinal cord is located. Pressure placed on the spinal cord causes pain and disruption to some body functions.

Learn about genetic disorders and conditions that affect growth and development.

Spondylolisthesis (or "slipped vertebra") is when one of the vertebrae slips forward and out of place on the vertebra beneath it.

Spondylolysis is when there is a defect of a narrow piece of bone in the vertebra.

Sprains are common injuries, especially among active older kids and teens who play sports.

Ankle sprains are common in kids and teens who play sports. They happen when the ligaments that support the ankle get overly stretched or torn.

A knee sprain happens when a ligament is stretched or torn because the knee gets twisted, bent, or hit.

A sprain is the stretch or partial tear of ligaments (which connect two bones). A wrist sprain happens when the ligaments that support the wrist bend or twist too far.

Learn about birth defects and congenital conditions that affect the feet and legs.

Learn about overuse injuries and conditions that affect the tendons and muscles.

A fractured patella is a broken kneecap (the flat, round bone that protects the knee joint).

Learn about arrhythmias and conditions that affect the heart and heartbeat.

See Polyarteritis Nodosa.

Learn more about pancreatitis, an inflammation of the pancreas that can cause severe belly pain and vomiting.

Learn about panic disorder, an anxiety disorder in which a person experiences recurrent feelings of intense fear when there's no real threat or danger.

Learn about causes of skin inflammation and conditions that affect infants and young children.

Learn about intestinal blockages and conditions that affect the digestive tract.

Parathesia is a burning, prickling, itching, or tingling "pins and needles" skin sensation. Anyone who has had a foot "fall asleep" has experienced temporary paresthesia.

Paronychia, an infection of the skin around a fingernail or toenail, usually isn't a serious problem.

Paroxysmal supraventricular tachycardia (PSVT) is a type of arrhythmia in which the heart beats very rapidly.

Patellar dislocation happens when the patella (kneecap) slips out of its normal position.

Learn about heart conditions that affect newborn and premature babies.

Learn more about pectus carinatum, commonly called pigeon chest.

Learn more about pectus excavatum, commonly called sunken chest.

Peptic ulcers are painful sores in the lining of the stomach or upper part of the small intestine.

See Polyarteritis Nodosa.

Learn about complications of infections and conditions that affect the heart.

Learn more about bacterial infections, problems of the gastrointestinal tract, and complications related to infections and diseases of the abdominal organs.

A peritonsillar abscess is an area of pus-filled tissue at the back of the mouth, next to one of the tonsils.

Learn more about this type of autism that can impair social skills, delay speech, and cause repetitive behaviors.

In this genetic disorder, the body cannot break down the amino acid phenylalanine, which then builds up in the system and affects the brain. Learn more.

Learn about phimosis, a condition that affects the penis and foreskin in uncircumcised males.

Learn more about skin infections, cysts, and abscesses.

Pinkeye (conjunctivitis) is an inflammation of the conjunctiva, the tissue covering the white part of the eye and the inner surface of the eyelid.

Pituitary dwarfism is a condition in which the pituitary gland does not make enough growth hormone, resulting in a child's slow growth pattern and unusually small stature.

Learn about rashes and other conditions that affect the skin.

Bacterial pneumonia is a lung infection caused by bacteria (such as staph or strep).

Mycoplasma pneumonia, also called walking pneumonia or atypical pneumonia, is a mild lung infection caused by bacteria.

Learn about viral pneumonia, a lung infection caused by a virus.

In this illness, something a person inhales can cause irritation and swelling in the lungs. Learn more here.

Pneumonitis is a general term for inflammation of the lungs.

Learn about polyarteritis nodosa (PAN), a rare disease causing inflammation of the blood vessels.

Polymyositis is an uncommon disease that causes muscle weakness, pain, and inflammation. It usually affects adults.

Learn about postoperative infections, which are any kind of infections that occur following a surgical procedure.

Postoperative pain is pain or discomfort after surgery.

Bimalleolar fracture, Pott's fracture, medial malleolus, lateral malleolus, ankle, ankle fracture, broken ankle, tibia, fibula, shinbone, operative fixation, surgery, malleoli

Learn about hormonal disorders and conditions that can affect childhood sexual development.

Primitive neuroectodermal tumors, or PNETs, are tumors that can happen anywhere in the brain or spine.

Learn about conditions that affect the rectum, anus, and digestive system.

See: Hypertension, Intracranial.

Learn about symptoms of mental illness and conditions that affect thinking and behavior.

With this condition, an artery carrying blood from the heart to the lungs can form a sling around the windpipe and block air flow. Learn more about it here.

Learn about this congenital heart defect that alters blood flow through the heart and lungs and can affect a child's growth and circulation.

See: Henoch-Schönlein Purpura (HSP).

See: Henoch-Schönlein Purpura (HSP).

See: Henoch-Schönlein Purpura (HSP).

See: Henoch-Schönlein Purpura (HSP).

Learn more about pyelonephritis and how it's treated.

Pyloric stenosis is a condition that happens during infancy, and affects the lower part of the stomach.

Pyogenic, or septic, arthritis is a serious and painful infection of a joint. It's most common in children from birth to age 3 and older adults.

Learn about pseudotumor cerebri, a disorder in which the pressure is too high in the fluid that surrounds the brain.

Asthma is a lung condition that causes difficulty breathing.

Learn more about asthma attacks, when asthma symptoms suddenly become severe.

Learn about causes of breathing difficulties and conditions that can affect the lungs and bronchi.

See: Bronchiectasis.

See: Bronchiectasis.

Learn about cystic fibrosis, an inherited disease primarily affecting the lungs and digestive system.

Learn more about difficult or labored breathing.

Hypoxemia is a condition in which there is a lower than normal level of oxygen in the blood.

Mycoplasma pneumonia, also called walking pneumonia or atypical pneumonia, is a mild lung infection caused by bacteria.

Learn about viral pneumonia, a lung infection caused by a virus.

Pneumonitis is a general term for inflammation of the lungs.

Learn what happens when the lungs cannot properly bring oxygen into or remove carbon dioxide from the blood.

Learn about RSV, a contagious infection that's a major cause of respiratory illness in young children.

Learn about abnormal immune system responses and disorders that can affect the lungs, lymph system, and other organs.

Learn more about this bacterial infection that can be transmitted from animals to humans.

Learn about complications of spinal cord injuries and conditions that affect the central nervous system.

A rash is an area of irritated, bumpy, painful, or swollen skin. Most aren't harmful or dangerous.

Learn about some common causes of rectal bleeding, most of which aren't serious.

Nursemaid's elbow is a partial dislocation of the elbow joint that happens when a ligament slips out of place near the elbow.

Diaper rash is a very common condition that can cause a baby's skin to become sore, red, and tender.

Learn about conditions that affect the rectum, anus, and digestive system.

Learn about potential complications of fetal development and conditions that affect the kidneys and urinary tract.

In this speech problem, problems in the structure, nerves, and muscles of the mouth and throat can change the quality of the voice. Read more.

Learn what happens when the lungs cannot properly bring oxygen into or remove carbon dioxide from the blood.

Learn about RSV, a contagious infection that's a major cause of respiratory illness in young children.

Retropharyngeal abscess is an area of infected, pus-filled tissue that forms in the deep tissues in the back of the throat.

Allergic rhinitis, sometimes called "hay fever" or seasonal allergies, are allergy symptoms that occur during certain times of the year.

Ringworm, or dermatophytosis, is a highly contagious infection of the skin, hair or nails caused by a type of fungus called a dermatophyte.

Roseola (also known as sixth disease) is a viral illness, most commonly affecting kids between 6 months and 2 years old.

Rotavirus is a highly contagious virus that can cause severe, frequent diarrhea, especially in young kids.

Seizures can be frightening, but most last only a few minutes and stop on their own.

A sore throat can be caused by many things, from viral and bacterial infections to seasonal allergies and gastroesophageal reflux.

Sanfilippo syndrome makes the body unable to break down certain carbohydrates (sugars) in the blood, leading to serious problems in the brain and nervous system.

Learn about abnormal immune system responses and disorders that can affect the lungs, lymph system, and other organs.

Learn about parasitic infections and skin disorders.

Learn about scarlet fever,an illness with a characteristic rash that is caused by a strep infection.

Learn about scoliosis, an abnormal curvature in the spine often detected just before puberty begins.

A variety of things can cause pain in the scrotum (also called scrotal pain), the pouch-like structure at the base of a boy's penis.

An absence seizure (also called a petit mal seizure) is type of epileptic seizure that causes a person to briefly lose consciousness and stare ahead without moving, appearing "absent."

See: Seizure, Tonic-Clonic.

See: Seizure, Petit Mal.

A tonic-clonic seizure (also called a grand mal seizure) is a sudden attack that brings on intense muscle spasms and loss of consciousness. It is caused by abnormal brain activity and affects the entire body.

Septic, or pyogenic, arthritis is a serious and painful infection of a joint. It's most common in children from birth to age 3 and older adults.

Learn about this condition, in which an infection can spread into the blood and cause serious health problems.

Sever disease is a painful bone disorder due to inflammation (swelling) of the growth plate in the heel.

See: Herpes Zoster.

Learn about sialadenitis, an infection of the saliva-producing glands.

Learn about genetic disorders and diseases and conditions that affect the blood.

Learn about genetic disorders and diseases and conditions that affect the blood.

See: Pilonidal Cyst.

Sinusitis is an infection that causes the sinuses (moist air spaces within the bones of the face around the nose) to swell or become irritated.

In slipped capital femoral epiphysis (SCFE), the very top of the thighbone (called the femoral head) slips out of line with the rest of the thighbone, causing a weakened hip joint.

Activities and sports that put stress on the back can lead to a slipped disc, which can cause pain in the back, arms, and legs.

A bite from a venomous (poisonous) snake or lizard is painful and also can be life threatening.

Spinal stenosis is a narrowing of the spaces in the spine, or backbone, where the spinal cord is located. Pressure placed on the spinal cord causes pain and disruption to some body functions.

Learn about chronic inflammatory diseases and conditions that affect the back and spine.

Learn about genetic disorders and conditions that affect growth and development.

Spondylolisthesis (or "slipped vertebra") is when one of the vertebrae slips forward and out of place on the vertebra beneath it.

Spondylolysis is when there is a defect of a narrow piece of bone in the vertebra.

Sprains are common injuries, especially among active older kids and teens who play sports.

Ankle sprains are common in kids and teens who play sports. They happen when the ligaments that support the ankle get overly stretched or torn.

A knee sprain happens when a ligament is stretched or torn because the knee gets twisted, bent, or hit.

A sprain is the stretch or partial tear of ligaments (which connect two bones). A wrist sprain happens when the ligaments that support the wrist bend or twist too far.

Learn about problems of the immune system and adverse reactions to drugs or infections.

Learn about stomatitis, an inflammation of the mouth.

Strabismus is when the eyes are not lined up correctly.

Strep throat, a painful throat infection, is common in kids and teens. It gets better quickly with antibiotic treatment.

Learn about this genetic disorder that can cause a birthmark on the face called a port-wine stain, as well as other symptoms.

A stye is a red, painful bump on the eyelid caused by a backed-up oil gland.

A subconjunctival hemorrhage is a harmless red spot on the white of the eye.

A subungual hematoma is blood trapped under a fingernail or toenail, often due to an injury such as a stubbed toe or a finger slammed in a door.

Syncope, or fainting, is a temporary loss of consciousness caused when blood flow to the brain suddenly drops, depriving the brain of oxygen.

Transient synovitis is a temporary inflammation of a joint, most often the hip, that usually does not cause any long-term problems.

Back pain is fairly common, and is often due to muscle strain or sprain. In students, wearing a heavy backpack is a common cause.

Belly pain is common and, most of the time, doesn't have a serious cause.

Most causes of chest pain in kids and teens are not serious and will clear up with minimal or no treatment.

Coughing is a symptom, not a disease, and sometimes can help clear the airway.

Babies use crying to communicate, and during the first 3 months of life, they cry a lot. Knowing what to expect can help parents and caregivers manage.

Diarrhea (loose, watery, or more frequent stools) can be a symptom of many conditions, including common infections. Most cases go away in a few days with proper home care.

Dizziness refers to feelings of lightheadedness, imbalance, or vertigo (the sensation that one’s surroundings are spinning or moving).

In most cases, fainting is not a sign of a dangerous problem, but should still be discussed with a doctor.

A fever itself is a symptom, causes no harm, and is often the body's way of fighting infections.

Headaches are common in kids and teens, and can have a wide range of causes. Most can be managed at home.

Malaise and fatigue are common symptoms of many ailments.

Nausea (stomach upset or feeling queasy) can be caused by many things. Often, it can be managed at home with treatment to prevent dehydration.

A rash is an area of irritated, bumpy, painful, or swollen skin. Most aren't harmful or dangerous.

Learn about some common causes of rectal bleeding, most of which aren't serious.

Seizures can be frightening, but most last only a few minutes and stop on their own.

A sore throat can be caused by many things, from viral and bacterial infections to seasonal allergies and gastroesophageal reflux.

See Dizziness.

Most cases of vomiting are due to viral gastroenteritis ("stomach flu") and can be managed at home with treatment to prevent dehydration.

Constipation -- having fewer and harder bowel movements (poops) than usual -- is rarely due to a serious condition.

Learn more about types of arrhythmias and problems of the heart.

Learn about birth defects and congenital conditions that affect the feet and legs.

Learn about overuse injuries and conditions that affect the tendons and muscles.

Testicular torsion is an emergency condition that happens when the spermatic cord gets twisted and cuts off blood supply, causing pain and swelling.

Tetanus, also known as lockjaw, is a serious but preventable disease that affects the body's muscles and nerves.

Learn about tetralogy of Fallot, a rare congenital heart disorder.

Learn about complications of spinal cord injuries and conditions that affect the central nervous system.

Thrush (candidiasis) is an overgrowth of a type of yeast, and commonly causes infections in the mouth, vagina, and skin.

Candidiasis is an overgrowth of a type of yeast, and commonly causes infections in the mouth, vagina, and skin.

A thyroid nodule is a lump in the thyroid gland.

Learn about conditions of the brain and nervous system and conditions related to ADHD and OCD.

See: Idiopathic Thrombocytopenic Purpura.

Learn more about diseases of the chest wall and conditions that cause chest pain.

Tinea capitis (ringworm of the scalp) is a fungal scalp infection that can be cured with medication.

Tinea corporis (ringworm) is a common skin infection that usually gets better with treatment.

Tinea cruris, also known as jock itch, is a skin infection of the groin area caused by several types of fungi often found on the skin.

Tonsillitis is an inflammation of the tonsils, the fleshy clusters of tissue in the back of the throat.

A primary tooth injury is an injury or damage to a child's primary (or "baby") tooth.

Secondary tooth injuries are injuries or damage to secondary or permanent teeth (also called "adult" teeth).

Learn about this condition, which affects neck muscles.

Learn about tracheitis, a condition that affects the respiratory tract.

Learn more about this medical procedure in which damaged stem cells in the blood are replaced with healthy stem cells.

See: Down Syndrome.

In the womb, a child's heart may develop a single large artery rather than separate aortic and pulmonary arteries. Learn about the condition here.

Learn about this genetic disorder that causes noncancerous tumors to grow in many parts of the body.

A tethered cord is when part of the spinal cord is attached inside the spinal canal, and the spinal cord is not able to move freely.

Learn more about this inflammatory disease of the large intestine, or colon.

Learn about disorders related to the umbilical cord and issues that affect newborn babies.

Undescended testis is a condition in which one or both of a boy's testicles (testes) have not moved into their proper place in the scrotum.

An upper respiratory infection (URI) can be caused by many viruses or bacteria. The common cold, croup, and sinusitis are all URIs.

Ureteroceles are caused by a birth defect in which the opening in the ureter is too small for urine to pass freely into the bladder.

Ureteropelvic junction obstruction is a partial or total blockage of the flow of urine in the area where a ureter attaches to a kidney.

Learn about bacterial infections and conditions that can affect the urinary tract.

Learn about urticaria, the red raised bumps or welts on the skin that are commonly called hives.

Learn more about conditions of the eyes and factors that may contribute to vision loss.

Learn more about conditions of the eyes and factors that may contribute to vision loss.

Learn more about conditions of the eyes and factors that may contribute to vision loss.

See Dizziness.

Most cases of vomiting are due to viral gastroenteritis ("stomach flu") and can be managed at home with treatment to prevent dehydration.

Vaginitis is an inflammation of the vagina.

Bacterial vaginosis (BV) is an infection in the vagina.

Bacterial vaginosis (BV) is an infection in the vagina.

Learn about viral infections, contagious diseases, and diseases that cause skin rashes.

Varices are swollen blood vessels that usually develop in the esophagus or stomach.

See: Varices.

See: Varicocele (Scrotal Varices).

A varicocele is an enlargement of the veins in the scrotum.

Venom refers to poisonous substances that are administered by an animal to its prey or enemy through a bite or sting. Depending on the species, its effects can range from mildly irritating to deadly.

Learn about congenital heart defects and conditions that affect the heart and circulatory system.

Learn about ventricular tachycardia, a potentially life-threatening arrhythmia in which the heart beats too rapidly.

Learn more about conditions and infections of the urinary tract and kidneys.

Learn about viral infections and causes of skin rashes.

A viral infection is a an infection caused by a virus (a type of germ).

Vitamin D deficiency is a condition that happens when a person isn't getting enough vitamin D, which is needed for strong bones and overall health.

Vitiligo is a loss of skin pigment that causes white spots or patches to appear on the skin.

Von Hippel-Lindau disease, or VHL, is a genetic disorder that causes blood vessels to grow abnormally.

Learn about warts, skin growths caused by viruses of the human papillomavirus (HPV) family.

A "wheeze" is a high-pitched whistling sound made when air flows through narrowed airways in the lungs.

Learn about Wolff-Parkinson-White Syndrome, a congenital heart condition that can cause an abnormally fast heart rhythm known as supraventricular tachycardia.

Wound dehiscence is a condition where a cut made during a surgical procedure separates or ruptures after it has been stitched back together.

Learn about this conditions that causes dry eyes.

Learn genetic disorders and conditions that can affect social and sexual development.

See: Candidiasis.

Learn about viral infections and diseases that can be transmitted from mosquitoes to humans.

See: Yersiniosis.

Learn more about bacterial infections and illnesses that result from improper food preparation.

Zika is a virus that a person can get from being bitten by an infected mosquito. The virus is of particular concern for pregnant women and women who may become pregnant.

Learn about viral infections and causes of skin conditions.

Learn more about diseases, infections, and conditions transmitted to humans from animals.