Quick action is essential during a serious allergic reaction. It helps to remind yourself of action steps so they become second nature if there's an emergency. Here's what to do.

Your eyes itch, your nose is running, you're sneezing, and you're covered in hives. The enemy known as allergies has struck again.

Doctors use several different types of allergy tests, depending on what a person may be allergic to. Find out what to expect from allergy tests.

Asthma makes it hard to breathe. Learn all about asthma here.

Visit our Asthma Center for information and advice on managing and living with asthma.

People who have celiac disease, a disorder that makes their bodies react to gluten, can't eat certain kinds of foods. Find out more - including what foods are safe and where to find them.

Find out if allergies can make a person's asthma symptoms worse.

Eczema is a common skin problem among teens. If you have eczema, read this article to find out more about it and how you can deal with the skin stress.

Living with an egg allergy means you have to be aware of what you're eating and read food labels carefully. Here are some tips for teens who have an egg allergy.

Doctors are diagnosing more and more people with food allergies. Knowing what to expect and how to deal with food allergies can make a big difference in preventing serious illness.

Taking precautions and carrying meds are just part of normal life for someone who has a food allergy. Here are some tips on how to make travel also feel perfectly routine.

With food allergies, preventing a reaction means avoiding that food entirely. But sometimes allergens can be hidden in places you don't expect. Here are tips on living with a food allergy.

Hives cause raised red bumps or welts on the skin. They're pretty common and usually not serious. Find out what to do about hives in this article for teens.

Asthma is more common these days than it used to be. The good news is it's also a lot easier to manage and control.

Going to the ER is the last resort for someone who has asthma. The good news is that you can prevent this by getting your asthma under control. Get some tips on how.

Milk is in all kinds of foods, even things like baked goods. So what should a person who's allergic to milk do?

Although food allergies are more common than ever, people who have them may feel different or embarrassed. A good friend can really help.

People who have HIV might feel alone and frightened at times. More than anyone, they need good friends like you to lean on and trust.

Find out what the experts have to say.

Peanuts are one of the most common allergy-causing foods, and they often find their way into things you wouldn't imagine. Learn the facts on living with a nut or peanut allergy.

About 60% to 80% of all people get a reaction to poison ivy. If you're one of them, check out these tips on what to do and how to avoid poison ivy.

Psoriasis causes skin cells to build up on the surface of the skin where they form itchy, red areas and thick scales. Find out how to deal with psoriasis, and what causes it, in this article for teens.

A person with severe allergies can be at risk for a sudden, serious allergic reaction called anaphylaxis. This reaction can seem scary, but the good news is it can be treated.

Shellfish allergies can be serious - and shellfish can appear in some surprising foods and products. Read about shellfish allergy and what to do when a reaction is severe.

Find out why smoking is a bad idea - especially for people with asthma.

This video shows what it's like to get a spirometry test.

Anemia is common in teens because they undergo rapid growth spurts, when the body needs more nutrients like iron. Learn about anemia, how to lower your risk of getting it, and how it's treated.

These videos show what's involved in getting a blood test and what it's like to be the person taking the blood sample.

Blood might look the same and do the same job, but tiny cell markers mean one person's body can reject another person's blood. Find out how blood types work in this article for teens.

There's a 97% chance that someone you know will need a blood transfusion. Blood donors — especially donors with certain blood types — are always in demand. Find out what's involved in this article for teens.

A person who has hemophilia has a tendency to bleed a lot. With new treatments, most people with hemophilia live pretty normal lives.

People with sickle cell disease need good friends who understand and can help them get through tough times. This article for teens helps you learn what you can do to be that friend.

Sickle cell crisis is when sickled cells clog small blood vessels, causing extreme pain and other symptoms. Learn more, including how to help prevent a crisis and what to do if one does happen.

Sickle cell disease is a blood disorder that causes red blood cells to change shape and cause problems. Find out more in this article for teens.

At a certain point, you'll no longer be able to see your childhood doctor. Here are tips for teens on making a smooth switch to adult sickle cell care.

When people have von Willebrand disease, their blood doesn't clot properly. Cuts and wounds can't scab over as well and they might bleed longer than normal. Find out more about von Willebrand disease in this article for teens.

Find out what the experts say.

Did you ever wonder what all those complex body systems do? Use this medical library to find out about basic human anatomy, how it all functions, and what happens when things go wrong.

Without blood, our organs couldn't get the oxygen and nutrients they need, we couldn't keep warm or cool off, we couldn't fight infections, and we couldn't get rid of our own waste products. Find out about the mysterious, life-sustaining fluid called blood.

Our bones, muscles, and joints form our musculoskeletal system and enable us to do everyday physical activities.

If the brain is a central computer that controls all the functions of the body, then the nervous system is like a network that relays messages back and forth to different parts of the body. Find out how they work in this Body Basics article.

Most people think digestion begins when you first put food in your mouth. But the digestive process actually starts even before the food hits your taste buds.

Hearing is their main job, but it's not all your ears do. Find out all about them in this body basics article for teens.

The endocrine system influences almost every cell, organ, and function of our bodies. It is instrumental in regulating mood, growth and development, metabolism, and sexual function, among other things.

Although your eyes are small, their structure is incredibly complex. Find out how they work in this body basics article.

Why do girls get periods? What goes on when a woman gets pregnant? What can go wrong with the female reproductive system? Find the answers to these questions and more in this article for teens.

The heart and circulatory system (also called the cardiovascular system) make up the network that delivers blood to the body's tissues.

The immune system is made up of special cells, proteins, tissues, and organs that defend people against germs and microorganisms. It's the body's defense against organisms and substances that invade our systems and cause disease.

The kidneys perform several functions that are essential to health, the most important of which are to filter blood and produce urine.

Each day you breathe about 20,000 times. Find out more about the lungs and breathing process.

What makes up a guy's reproductive system and how does it develop? Can anything go wrong? Find the answers to these questions and more in this article.

Your body gets the energy it needs from food through a process called metabolism. Get all the facts on metabolism in this article.

Did you know that your mouth is the first step in the body's digestive process? Or that the mouth and teeth are essential for speech? Learn about the many roles your mouth and teeth play.

Our skin protects the network of tissues, muscles, bones, nerves, blood vessels, and everything else inside our bodies. Hair and nails are actually modified types of skin.

The lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections.

If the tendon just above your heel becomes swollen or irritated due to overuse, it can lead to a painful condition called Achilles tendonitis. Find out how to treat it - and prevent it.

A sprained ankle is a very common injury that happens when the ligaments that support the ankle get overly stretched or torn. Find out how to avoid ankle sprains and what to do if you get one.

ACL injuries - which can happen in active and athletic people - happen when excessive pressure is put on the knee joint, resulting in a torn ligament.

Blount disease is a growth disorder that affects the bones of the lower leg. It causes bowing of the leg below the knee, which gets worse if it's not treated.

Bones are tough stuff - but even tough stuff can break. Find out what happens when a bone fractures.

A broken collarbone is one of the most common types of broken bones. Find out how it can happen - and how to treat and avoid fractures.

Bursitis, an irritation of the small fluid sacs that provide cushioning in some joints, is often caused by sports-related injuries or repeated use of a particular joint.

This article for teens has tips on taking care of a cast so it keeps working as it should.

Ira has cerebral palsy (CP), but it doesn't interfere with his love of sports or his dream of being a broadcaster. Check out this video.

Costochondritis is a fairly common cause of chest pain. It's not serious, but it can be scary. Find out what it is, and what to do if you think you have it.

Female athlete triad is a combination of three conditions: disordered eating, amenorrhea (loss of a girl's period), and osteoporosis (a weakening of the bones).

Fibromyalgia is a long-term condition that causes pain in a person's muscles, joints, and other soft tissues. Find out how doctors tell if a person has fibromyalgia and what can be done to treat it.

A broken bone requires emergency medical care. Here's what to do.

A groin strain is a tear of one or more of the muscles that help you squeeze your legs together. Find out what to do for groin strains - and why it's important not to go back to sports or other activities too quickly.

Guillain-Barré syndrome is very rare. It can be frightening because it can cause weakness and even paralysis. Luckily, most people who get GBS recover.

A hamstring strain happens when one or more of the muscles in the back of the leg gets stretched too far and starts to tear. Find out how to treat hamstring strains in this article for teens.

Most hip pointer injuries can be easily treated and heal in their own time. Find out what to do in this article for teens.

Learn about juvenile idiopathic arthritis, a specific kind of arthritis that usually occurs in kids and teens younger than 17.

Caroline loved sports. But when an ongoing knee injury kept her from playing the sports she loved, she discovered new interests. Read her story.

Your spine, or backbone, normally curves forward gently as it runs up your back. Sometimes, though, someone's back can be rounded too far forward, which is a condition known as kyphosis.

Lupus is a disease that affects the immune system. Learn how lupus is treated, signs and symptoms, how to support a friend who has it, and more.

MCL injuries happen when excessive pressure is put on the knee joint, causing a torn ligament.

Medial epicondylitis is an overuse injury that affects the tendons in the elbow. It's rarely serious, but it does need rest and treatment or it will get worse. Find out what to do.

The key to healing meniscus tears is not to get back into play too quickly. Find out what meniscus tears are and how to treat them.

Muscular dystrophy is a disorder that weakens a person's muscles over time. People who have the disease can gradually lose the ability to do everyday tasks.

Osgood-Schlatter disease (OSD) is an overuse injury that can cause knee pain in teens, especially during growth spurts. Learn more.

Sometimes a bad cut that gets infected can lead to even worse things, like a bone infection called osteomyelitis. The easiest way to protect yourself is to practice good hygiene.

The most obvious symptom of plantar fasciitis is a sharp pain on the bottom of the foot, near the heel. Find out how to tell if it's plantar fascitiis and what you can do in this article for teens.

In teens, biceps tendonitis is usually an overuse injury that causes tendons in the upper arm to be swollen or irritated. Most cases heal on their own if you follow a few guidelines from your doctor.

Quadriceps contusions are common in sports that have a lot of direct contact or a chance of collisions or wipeouts. Find out what to do if you get one - and how to avoid them.

Repetitive stress injuries happen when too much stress is placed on a part of the body, causing problems like swelling, pain, muscle strain, and tissue damage.

Scoliosis makes a person’s spine curve from side to side. Large curves can cause health problems like pain or breathing trouble. Health care providers treat scoliosis with back braces or surgery when needed.

Some teens with scoliosis wear a brace to help stop their curve from getting worse as they grow. Find out more about how scoliosis braces work and how long people wear them in this article for teens.

This growth-related injury is more common in teens who play sports that require a lot of running or jumping. Find out why it happens - and what you can do to avoid and treat it.

A good, stable connection at your hip joint is what lets you walk, run, make that jump shot, and shake it on the dance floor. But in some teens – particularly those who are obese – the hip joint is weakened by slipped capital femoral epiphysis (SCFE).

A spinal fusion is a surgical procedure that's done to stabilize or straighten the bones in the back. It can help some teens with scoliosis.

Steven was diagnosed with SMA when he was 3. Here's a look at his life today and why he says, "When someone tells you you can't do something, don't be afraid to try something new."

Sprains and strains are common injuries, especially for people who play hard or are into sports. Find out what they are and how to recuperate from one.

It's not always easy to tell if you have a stress fracture, and stress fractures can get worse quickly. This article explains how to prevent and treat them.

Find out what the experts have to say.

If you tore your ACL, you might need this surgery to fix it. Find out what's involved.

You probably can't wait to get back to your normal activities, but it takes a while for a limb that's been in a cast to finish healing. Here's what to expect.

Bell's palsy is a temporary weakness or paralysis of the muscles on one side of the face. Although it doesn't happen to many people, it can be scary. This article for teens covers the facts.

Cerebral palsy is one of the most common developmental disabilities in the United States. It affects a person's ability to move and coordinate body movements.

Ira has cerebral palsy (CP), but it doesn't interfere with his love of sports or his dream of being a broadcaster. Check out this video.

Keith has cerebral palsy. This is his story about life in high school, dating, sports, and taking chances.

How can you tell if you have a concussion? What should you do? And what's going to happen with sports and school? The facts are all on this site for teens.

Alex plays high school football, track, basketball, and lacrosse. He's had two concussions. Here, he talks about his experience and what he learned.

All body parts take time to heal, even brains.This article for teens has tips on what doctors often recommend to help people heal from a concussion.

In a concussion, the brain shifts inside the skull. This can cause a sudden - but usually temporary - disruption in a person's ability to function properly and feel well. Here's what to do if you suspect a concussion.

Seizures are a common symptom of epilepsy, a condition that affects millions of people worldwide. Learn all about epilepsy, including what to do if you see someone having a seizure.

Fainting is pretty common in teens. The good news is that most of the time it's not a sign of something serious.

Guillain-Barré syndrome is very rare. It can be frightening because it can cause weakness and even paralysis. Luckily, most people who get GBS recover.

Almost everyone gets headaches. So how do you know if a headache is just a passing pain or something more?

Lyme disease can be treated if it's caught early. Find out what causes it, how it's treated, and how to prevent it.

If you've ever had a migraine, you know that these headaches can cause severe pain and other symptoms. Read about migraine causes, treatments, prevention tips, and lots more.

A concussion can affect you at school because it's a type of brain injury. Doing schoolwork and being in a classroom can sometimes make things worse. Here's what to know about school and concussions.

As long as people play sports, there will be concussions from time to time. Find out how to protect yourself and what to do if you get a concussion playing sports.

A tic is a sudden, repetitive movement or sound that some people make, which can be difficult to control.

Tourette syndrome affects the body's brain and nervous system by causing tics - repeated, uncontrollable movements or involuntary vocal sounds.

Is the thought of Lyme disease making you feel you'll be safer in the comfort of your room than the great outdoors? This info can help you know if you're at risk for Lyme disease.

There's no one reason why people get depressed - many different things can play a role. Find out more about the things that can trigger depression.

Find out what the experts have to say.

When chemotherapy and other treatments attack cancer cells, they can affect some of the body's healthy cells too. As a teen, you'll want to know what this can mean to your fertility.

Get the basics on cancer and cancer treatments in this article.

Visit our Cancer Center for teens to get information and advice on treating and coping with cancer.

Chemotherapy, or chemo, is the use of medications to treat cancer. This article explains how chemo works and what to expect when getting treatment.

It's unusual for teens to have cancer, but it can happen. The good news is that most will survive and return to their everyday lives. Learn about how to cope if you or someone you know has cancer.

Hodgkin's disease is a type of lymphoma, which is a cancer of the lymphatic system. Although cancer can seem scary, most teens who get Hodgkin's disease get better.

Melanoma is different from other skin cancers because it can spread if it's not caught early. Find out how to lower your risk of getting melanoma and how doctors treat it.

It's hard to know how to respond when someone you love — someone your own age — is diagnosed with cancer. Here are some thoughts on dealing with feelings and helping your friend.

Non-Hodgkin lymphoma is a disease in which cancer cells form in a person's lymphatic system and start to grow uncontrollably.

More than half of all people with cancer are treated with radiation therapy. Get the facts on radiation therapy, including what it is, what to expect, and how to cope with side effects.

If your doctor prescribed steroids as part of your treatment for an illness, don't worry. It's not the illegal, doping scandal kind of steroid. Get the details in this article for teens.

While cancer is rare in teens, some types are more likely to affect young people. Learn about these types of cancer, including warning signs, symptoms, and treatments.

Cancer patients often have to stay at home to avoid infection. Read our ideas on ways to make the best of your time at home.

People who have celiac disease, a disorder that makes their bodies react to gluten, can't eat certain kinds of foods. Find out more - including what foods are safe and where to find them.

Cholera is an intestinal infection that mostly affects people in tropical regions. Find out more about cholera in this article for teens.

Constipation is a very common problem that usually happens because a person's diet doesn't include enough fluids and fiber. In most cases, making simple changes can help you feel better.

Crohn's disease is a condition that causes parts of the intestine (bowel) to get red and swollen. It can be challenging to deal with, but many teens find that they're able to feel well and have few symptoms for long periods of time.

Cystic fibrosis (CF) is an inherited disease that causes the body to produce mucus that's extremely thick and sticky. It mainly affects the lungs and the pancreas, causing serious breathing and digestive problems.

Like every other teenager, girls and guys with CF need calories to fuel their growth. They just need more of them - sometimes as much as 30% to 50% more calories than other teens.

This sample meal plan for teens with cystic fibrosis provides a day's worth of meals that add up to about 3,750 calories.

A hernia is an opening or weakness in the wall of a muscle, tissue, or membrane that normally holds an organ in place. Learning to prevent hernias isn't hard to do - check out these tips.

Indigestion is just another name for an upset stomach. It usually happens when people eat too much or too fast, or have foods that don't agree with them.

Inflammatory bowel disease is an ongoing illness caused by an inflammation of the intestines. There are two kinds of IBD: Crohn's disease and ulcerative colitis.

For some people stomachaches and diarrhea are a regular occurrence. Read this article for information on irritable bowel syndrome (IBS), a common intestinal disorder that affects the colon.

If you have lactose intolerance, you're not alone. Millions of Americans have the condition. Check out these tips on dealing with lactose intolerance.

Lots of different problems can cause similar kinds of stomach pain - not all of them related to the digestive system. Here are some clues about what could be going on.

A worm that grows in the intestines by eating your food is pretty icky to think about. This article provides the basics on tapeworm infections and how to prevent them.

Ulcerative colitis is a type of inflammatory bowel disease (IBD) that happens only in the colon. It causes the inner lining of the colon to get red and swollen with sores called ulcers.

Doctors once thought that stress, spicy foods, and alcohol caused most stomach ulcers. But ulcers are actually caused by a particular bacterial infection, by certain medications, or from smoking. Read all about ulcers.

This video shows what it's like to get an upper GI test.

Visit our Asthma Center for information and advice on managing and living with asthma.

Visit our Cancer Center for teens to get information and advice on treating and coping with cancer.

Chronic fatigue syndrome (CFS) is a complicated disease for doctors to diagnose — and even fully understand. Find out more about this often misunderstood condition.

Our Diabetes Center provides information and advice for teens about treating and living with diabetes.

Gastroesophageal reflux disease doesn't just affect old people who eat too much while watching TV. Active, healthy teens can have GERD too.

Visit our center on managing your medical care for advice on how to get involved in taking charge of your health and choosing the right health care providers.

Humans, animals, and even plants can have albinism, a condition that gives people a kind of pale appearance. Find out more about albinism here.

A dwarf is a short-statured person whose adult height is 4 feet 10 inches or under. Find out what happens when a person has dwarfism and why some people are born with it.

Emily was adopted from Russia, where she was born with a type of dwarfism. In this video, she talks about her life philosophy and how she overcame the many hurdles she faced.

A person who has hemophilia has a tendency to bleed a lot. With new treatments, most people with hemophilia live pretty normal lives.

This genetic condition only affects guys and is also called "XXY." It can affect a guy's ability to learn and his sexual development, but doctors can treat it. Find out more.

Marfan syndrome affects the body's connective tissue and can cause problems in the eyes, joints, and heart. But teens with Marfan syndrome can live normal lives. Find out how in this article.

Metabolic syndrome is a signal that someone could be on the road to serious health problems. Find out more in this article for teens.

Muscular dystrophy is a disorder that weakens a person's muscles over time. People who have the disease can gradually lose the ability to do everyday tasks.

Genes play an important role in how we look and act, and even in whether we get sick. This article gives the lowdown on genes, genetic disorders, and new research into gene therapy.

The thyroid gland manufactures the hormones that help control metabolism and growth. So if your thyroid isn't operating properly, you can have problems in other parts of your body.

Check out these definitions to help you understand the thyroid gland and thyroid disease.

Turner syndrome is a genetic disorder that affects about 1 in every 2,500 girls. Learn more about the condition and how doctors treat it.

When people have von Willebrand disease, their blood doesn't clot properly. Cuts and wounds can't scab over as well and they might bleed longer than normal. Find out more about von Willebrand disease in this article for teens.

Lots of people wonder if they have hypoglycemia, but the condition is not common in teens. Get the facts on hypoglycemia.

Find out what the experts say.

The things you do now could help prevent diabetes later, depending on the type of diabetes. Here's the scoop on diabetes prevention.

Find out what the experts have to say.

Our Diabetes Center provides information and advice for teens about treating and living with diabetes.

DJ has type 2 diabetes. In this video, he talks about how he adjusted and what's working when it comes to taking care of himself.

Marco, 18, was diagnosed with diabetes 2 years ago. He talks about adjusting to life with diabetes and preparing to go to college.

A dwarf is a short-statured person whose adult height is 4 feet 10 inches or under. Find out what happens when a person has dwarfism and why some people are born with it.

In most cases, teens who are small are just physically maturing a bit more slowly than their friends. Occasionally, though, there's a medical reason why some kids and teens stop growing. Find out about growth problems and how doctors can help.

Sure, you've heard of diabetes. But how much do you really know about what it's like to have it? Read our tips on helping a friend with diabetes.

The thyroid gland manufactures the hormones that help control metabolism and growth. So if your thyroid isn't operating properly, you can have problems in other parts of your body.

Check out these definitions to help you understand the thyroid gland and thyroid disease.

People with type 1 diabetes need to follow a treatment plan to manage their diabetes and stay healthy and active.

Diabetes is a disease that affects how the body uses glucose, a sugar that is the body's main source of fuel. In type 1 diabetes, glucose can't get into the body's cells where it's needed.

People with type 2 diabetes need to follow a plan to manage their diabetes and stay healthy and active.

Teens with type 2 diabetes have to pay close attention to what they eat and do.

Arrhythmias are abnormal heartbeats usually caused by an electrical "short circuit" in the heart. Many are minor and not a significant health threat, but others can indicate a more serious problem.

Atrial septal defect, or ASD, is a heart defect that some people are born with. Most ASDs are diagnosed and treated successfully with few or no complications.

Doctors use cardiac catheterization to gather information about the heart and blood vessels as well as treat certain heart conditions. Find out what's involved.

When someone has coarctation of the aorta, that person's aorta (the major blood vessel that carries blood away from the heart to the body) is narrowed at some point.

An echocardiogram (also called an echo or cardiac ultrasound) uses sound waves to create pictures of the heart. See why doctors might order this test for teens.

This video shows what it's like to have an electrocardiogram (EKG for short).

High blood pressure, also called hypertension, is more common in adults, but it can happen at any age. Learn what it is, how to prevent it, and how to treat it.

Postural orthostatic tachycardia syndrome (POTS) happens when the autonomic nervous system doesn't work as it should. It can make someone feel lightheaded or pass out every time they stand.

Ventricular septal defect, or VSD, is a heart condition that a few teens can have. Find out what it is, how it happens, and what doctors do to correct it.

Bedwetting can be embarrassing and upsetting for teens, but there are effective ways to correct the problem and scientists are constantly developing new treatments.

Hematuria is pretty common, and most of the time it's not serious. Find out what causes blood in the urine and what to do about it.

Dialysis is a medical treatment that can take over the job of filtering the blood until a person's failing kidneys heal or are replaced with a kidney transplant. Find out more in this article for teens.

With glomerulonephritis, tiny filtering units in the kidneys stop working properly, causing problems like too much fluid in the body and swelling. Most of the time it can be treated. Find out more.

Hemodialysis is the type of kidney dialysis that doctors use most to take over the kidneys' job of filtering the blood. Find out more in this article for teens.

Sometimes, the kidneys aren't able to do their job properly. Other than kidney infections, the two most common kidney conditions among teens are nephritis and nephrosis.

Kidney stones mostly happen to adults, but sometimes teens can get them. Find out what kidney stones are, how to treat them, and ways to help prevent them.

If the kidneys stop working, a person will need either dialysis or a transplant. Get the facts on kidney transplant in this article for teens.

This medical treatment helps people with kidney failure. It can be done at home, often overnight, to take over the kidneys' job of filtering blood. Find out more in this article for teens.

A urinary tract infection (UTI) is one of the most common reasons that teens visit a doctor. Learn about the symptoms of UTIs, how they're treated, and more in this article.

ADHD is a medical condition that affects how well someone can sit still, focus, and pay attention. This article for teens has the basics on ADHD.

Medicine doesn’t cure ADHD. But it does help boost a person's ability to pay attention, slow down, and have more self-control. This article for teens has details on how ADHD medicines help.

There's no quick fix for ADHD. But taking medicine and working with counselors can help. This article for teens has tips for handling school and relationships.

Autism can make communicating and interacting with other people difficult. Find out more.

Learning disabilities affect the brain's ability to receive, process, analyze, or store information. These problems can make it difficult for a student to learn as quickly as others - but they have nothing to do with a person's intelligence.

Therapy is part of the treatment for most people diagnosed with ADHD. This article is for teens who want to know what to expect from therapy and how it works for ADHD.

Dyslexia is a learning disability in which people have difficulty learning to read, even though they are smart enough and are motivated to learn. Learn more about dyslexia and how to deal with it.

Asthma makes it hard to breathe. Learn all about asthma here.

Bronchitis is an inflammation of the lining of the bronchial tubes. When a person has bronchitis, it may be harder for air to pass in and out of the lungs.

Cystic fibrosis (CF) is an inherited disease that causes the body to produce mucus that's extremely thick and sticky. It mainly affects the lungs and the pancreas, causing serious breathing and digestive problems.

An incentive spirometer is a way to do breathing exercises to help with healing after surgery or to manage an illness. This article explains how to use an incentive spirometer.

An incentive spirometer is a way to do breathing exercises to help with healing after surgery or to manage an illness. This article explains how incentive spirometry works.

Tuberculosis (TB) is making a comeback in the United States today - particularly among the homeless, those in prison, and those rendered susceptible because of HIV infection.

An asthma flare-up (or attack) can cause coughing, chest tightness, wheezing, and trouble breathing. Sometimes, symptoms can be severe. Find out what causes flare-ups and what you can do.

This video shows what it's like to get an X-ray.

If you're afraid of shots, you're not alone. Next time your doc asks you to roll up your sleeve, try these tips.

These videos show what's involved in getting a blood test and what it's like to be the person taking the blood sample.

Doctors use cardiac catheterization to gather information about the heart and blood vessels as well as treat certain heart conditions. Find out what's involved.

This video shows what it's like to get a CAT scan.

An echocardiogram (also called an echo or cardiac ultrasound) uses sound waves to create pictures of the heart. See why doctors might order this test for teens.

This video shows what it's like to have an electrocardiogram (EKG for short).

If you need medical care but don't think you can afford it, you're not alone. Get tips on finding low-cost or free care in this article for teens.

Find out what the experts have to say.

This video shows what it's like to get an IV.

This video shows what it's like to get an MRI.

A spinal fusion is a surgical procedure that's done to stabilize or straighten the bones in the back. It can help some teens with scoliosis.

This video shows what it's like to get a spirometry test.

This video shows what it's like to get a strep test.

This video shows what it's like to get an upper GI test.

This video shows what it's like to get a urine test.

This video shows what it's like to get an X-ray.

When Rachel got her braces off during her junior year in high school, she finally had the smile she'd always wanted. So what went wrong? Read her story to find out.

Canker sores are fairly common, and they usually go away on their own without treatment. Read this article for teens to find out more, including tips on what to do about the pain.

Gum disease doesn't just happen to people your grandparents' age - it can happen to teens too. Get the details here.

A peritonsillar abscess is an area of pus-filled tissue at the back of the mouth, next to one of the tonsils. Find out how it happens and what to do.

TMJ disorders are medical problems related to the joint that connects the lower jaw to the skull. They can cause pain, difficulty chewing, and other problems.

Find out what the experts have to say.

Bad breath, or halitosis, can be a major problem, especially when you're about to snuggle with your sweetie or whisper a joke to your friend. The good news is that bad breath often can be easily prevented.

Here are 5 practical tips on goal setting that can help make it easier to set and reach goals.

We use the words "oveweight" and "obese" a lot, but they actually have medical meanings. Find out how doctors diagnose these conditions and what they mean for a person's health.

Acanthosis nigricans, or AN, is a darkening and thickening of the skin that can be a sign of certain other medical conditions. Find out more.

One of the biggest questions guys and girls have as they grow and develop is whether they're the right weight. One place to start is by learning about body mass index, or BMI.

Cholesterol is a type of fat found in your blood. The body needs some cholesterol, but too much can be a problem. Discover more about cholesterol in this article for teens.

If a person is struggling with extra weight, it can add to the emotional ups and downs of being a teen. Get some tips on coping here.

We've all eaten a whole bag of chips out of boredom or while cramming for a big test. Learn more about emotional eating, and how to manage it, in this article for teens.

Keeping an exercise log is a great way to stay motivated and reach exercise goals.

Keeping an exercise log is a great way to stay motivated and reach exercise goals.

A food journal can help us track our eating as well as see connections between our feelings and food.

There are several different types of weight loss surgeries. One type is gastric sleeve surgery, also known as sleeve gastrectomy. Find out what's involved and who gets it in this article for teens.

Looking for an easy way to eat healthier? This article provides tips on choosing the right foods - and an easy-to-follow chart to guide you.

Anyone who has tried to lose weight knows it can be a struggle. The best way to lose weight is to focus on making small, specific changes that are easy to stick with in the long run. Use our plan to get there!

Lots of people are unhappy with their present weight, but aren't sure how to change it - or even if they need to. Get the facts on weight loss here.

High blood pressure, also called hypertension, is more common in adults, but it can happen at any age. Learn what it is, how to prevent it, and how to treat it.

Find out what the experts have to say.

Brandon, 17, has lost 70 pounds through better eating and exercise. In this video he talks about what inspired him and how he stayed on track.

Has your doctor told you to lose weight? Get ideas on food, fitness, and staying motivated. We've also got weight management tools and recipes designed just for teens.

Metabolic syndrome is a signal that someone could be on the road to serious health problems. Find out more in this article for teens.

In polycystic ovary syndrome, the ovaries produce higher than normal amounts of certain hormones, which can interfere with egg development and release. Learn how doctors diagnose and treat PCOS.

Losing weight can feel like a challenge, no matter how much we want it. It can sometimes seem like our minds are working against us. That's where weight-management counselors can help.

Teens with type 2 diabetes have to pay close attention to what they eat and do.

Weight loss surgery works. But it's serious stuff, both physically and emotionally. Find out about different weight loss surgery options for teens.

These videos guide teens through basic strength training exercises. Anyone can do these exercises, and they work well as part of a weight-loss plan.

See what the experts have to say.

A couple of pounds of extra body fat are not a health risk for most people. But when people are severely overweight, it can cause health problems.

Doctors may do weight loss surgery if someone who is very overweight has tried but failed to lose weight and faces serious medical problems. Find out what makes teens eligible for bariatric surgery.

Getting the right amount of exercise can rev up your energy levels and even help you to feel better emotionally. Find out why.

Find out what the experts have to say.

Kayla lost her hair, but that didn't stop her from winning beauty pageants. Read how the winner of the Miss Delaware crown relied on confidence and leadership to stand above the crowd.

Rachel developed an anxiety disorder during her junior and year of high school. Today she's in college and enjoying life. Read her story.

Jordan has had asthma since age 2. In this video for teens he talks about what he did to get it under control.

Monica, 17 developed asthma when she was 14. In this video, she talks about how she adapted to life with asthma.

When Rachel got her braces off during her junior year in high school, she finally had the smile she'd always wanted. So what went wrong? Read her story to find out.

Keith has cerebral palsy. This is his story about life in high school, dating, sports, and taking chances.

Alex plays high school football, track, basketball, and lacrosse. He's had two concussions. Here, he talks about his experience and what he learned.

DJ has type 2 diabetes. In this video, he talks about how he adjusted and what's working when it comes to taking care of himself.

Marco, 18, was diagnosed with diabetes 2 years ago. He talks about adjusting to life with diabetes and preparing to go to college.

Emily was adopted from Russia, where she was born with a type of dwarfism. In this video, she talks about her life philosophy and how she overcame the many hurdles she faced.

Caroline loved sports. But when an ongoing knee injury kept her from playing the sports she loved, she discovered new interests. Read her story.

Steven was diagnosed with SMA when he was 3. Here's a look at his life today and why he says, "When someone tells you you can't do something, don't be afraid to try something new."

In this video, teens talk about dealing with various health problems as well as fitting healthy eating and exercise into their lives.

If periods aren't regular it's usually because a girl's body is still developing. But sometimes, changes in blood flow can be a sign of abnormal uterine bleeding (AUB).

It's rare for teen girls to have breast problems. But sometimes a doctor or nurse might think a breast exam is a good idea. Find out why, as well as what's involved in a breast exam.

Find out what the experts have to say.

Many girls have to deal with PMS, cramps, or headaches around the time of their periods. These problems are usually nothing to worry about. Get the facts on which period problems are normal and which ones might indicate something's going on.

Concerned about your growth or development? Puberty can be delayed for several reasons. Luckily, doctors usually can help teens with delayed puberty to develop more normally.

Read this article to learn all about endometriosis and how doctors help girls who have it.

Female athlete triad is a combination of three conditions: disordered eating, amenorrhea (loss of a girl's period), and osteoporosis (a weakening of the bones).

AIDS, or acquired immunodeficiency syndrome, is a disease where the body is unable to fight off many infectious diseases as it normally could. Find out how AIDS is spread and how to protect yourself against it.

This genetic condition only affects guys and is also called "XXY." It can affect a guy's ability to learn and his sexual development, but doctors can treat it. Find out more.

A pelvic exam is where a doctor or nurse practitioner looks at a girl's reproductive organs (both outside and internally) and feels the uterus and ovaries to be sure everything's normal. Find out what's involved in this article for teens.

In polycystic ovary syndrome, the ovaries produce higher than normal amounts of certain hormones, which can interfere with egg development and release. Learn how doctors diagnose and treat PCOS.

Serious testicular injuries are relatively uncommon, but testicular injury can be painful. Read this to find out what steps you can take to protect yourself from injury.

This emergency condition happens when the spermatic cord gets twisted and cuts off blood supply, causing pain and swelling. Find out what to do in this article for teens.

Turner syndrome is a genetic disorder that affects about 1 in every 2,500 girls. Learn more about the condition and how doctors treat it.

A varicocele is an enlargement of the veins in the scrotum. Although there is no way to prevent a varicocele, it usually needs no special treatment.

Find out what the experts have to say.

Find out what the experts have to say.

Cleft lip and palate are birth defects that happen while a baby is still developing in the womb. Find out more about cleft lip and palate and some of the challenges they present.

A corneal abrasion happens when something cuts, scratches, or scrapes the cornea (the clear tissue covering the eye). Most will heal in a couple of days.

Earbuds are basically a tiny pair of speakers that go inside the ears. They're fine at low volumes, but they can cause permanent hearing loss if not used properly. Find out what's safe (and not) in this article for teens.

Want to hear what's being said to you, by you, and about you? Find out how hearing aids help people with certain types of hearing loss.

Hearing impairment occurs when there's a problem with or damage to one or more parts of the ear. Find out its causes and what can be done to help correct it.

Find out what the experts have to say.

Perforated eardrums can really hurt. And if you can't hear as well as usual, they can be scary. The good news is, most people who have them get all their hearing back eventually.

Do you know someone who stutters or has another speech disorder? Find out how speech disorders are treated, how you can help a friend or classmate cope, and lots more.

A stye is a backed-up oil gland in the eyelid. Styes are usually easy to get rid of, but there are some things you can do to help. Learn more about styes.

When one or more parts of the eye or brain that are needed to process images become diseased or damaged, severe or total loss of vision can occur. Read all about visual impairment.

People can get abscesses on the skin, under the skin, in a tooth, or even inside the body. Most abscesses are caused by infection, so it can help to know what to do. Find out in this article for teens.

Acanthosis nigricans, or AN, is a darkening and thickening of the skin that can be a sign of certain other medical conditions. Find out more.

Kayla lost her hair, but that didn't stop her from winning beauty pageants. Read how the winner of the Miss Delaware crown relied on confidence and leadership to stand above the crowd.

Although the name athlete's foot sounds funny, if you have this skin infection, you're probably not laughing. The good news is that it is generally easy to treat.

Blisters, calluses, and corns can be uncomfortable, but they're also pretty common and easy to prevent. Find out what to do in this article for teens.

This article is all about bruises, including why they happen, how to make them go away faster, and why they turn all those funny colors.

Scars from acne can seem like double punishment - first you had to suffer through the pimples, now you have marks to remind you. Is there anything you can do?

There's no sure way to prevent acne. But these tips might help reduce the number and severity of your breakouts.

Cellulite, the lumpy substance resembling cottage cheese that is commonly found on the thighs, stomach, and butt, is actually a fancy name for collections of fat that push against the connective tissue beneath your skin.

Most small cuts, scrapes, or abrasions heal on their own. Here are tips for teens on how to treat cuts at home - and when to get medical help.

If you're worried about dandruff, you're not alone. Dandruff can start in puberty, and lots of teens and adults live with it. Learn how to control it in this article for teens.

Erythema multiforme is a rash that appears as red, target-shaped ("bulls-eye") patches or sores on the skin. Find out what causes it - and what to do - in this article for teens.

Baldness or hair loss may seem like something only adults need to worry about. But when teens lose more than the usual amount of hair, it may mean that something is going on.

Lice aren't dangerous, but they do spread from person to person easily. They can also be hard to get rid of. Find out how to prevent lice -- and what to do if someone you know has them.

Hives cause raised red bumps or welts on the skin. They're pretty common and usually not serious. Find out what to do about hives in this article for teens.

Find out what the experts have to say.

A toenail is ingrown when it begins to break through and grow into the soft skin of the toe. Find out more about ingrown toenails.

Jock itch is a pretty common fungal infection of the groin and upper thighs. It is generally easy to treat - and avoid - by following a few simple steps.

The name sounds dramatic, like a Harry Potter spell. Luckily, molluscum contagiosum isn't a big deal. Find out what to do about it in this article for teens.

You may be surprised that some of the things you've heard about acne - like what causes it and how to deal with it - aren't true.

Paronychia is an infection of the skin around a fingernail or toenail. Most of the time, it's not serious. Find out what causes it, what to do, and how to prevent it.

Pityriasis rosea is a pink or gray skin rash that's common in teens and young adults. It may itch, but it's harmless. Find out what to do about it in this article for teens.

Psoriasis causes skin cells to build up on the surface of the skin where they form itchy, red areas and thick scales. Find out how to deal with psoriasis, and what causes it, in this article for teens.

Ringworm isn't a worm at all - it's the name for a type of fungal skin infection. The good news is that ringworm is easy to treat.

Shingles is rare in teens with healthy immune systems, and mostly affects older adults. But it's good to know the basics about this skin rash, which is caused by the same virus that causes chickenpox.

Vitiligo is a loss of skin pigment that causes white spots or patches to appear on the skin. It's not medically dangerous, but it can affect a person's appearance. Find out more.

Find out what the experts have to say.

Almost every teen gets acne at some point. This article addresses common questions and concerns about acne and tells you what you can do about it.

How well a wound heals depends on where it is on the body and what caused it – as well as how well someone cares for the wound at home. Find out what to do in this article for teens.