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What Are Allergies?

An allergy (say: AL-ur-jee) is when your immune system overreacts to something harmless that it thinks is dangerous. Normally, your immune system protects you by fighting germs. But when you have allergies, it overreacts and tries to "fight" ordinary things like grass, animal hair, or some foods. This causes the sneezing, itching, and other reactions that you get with allergies.

What Causes Allergies?

The things that cause allergies are called allergens (say: AL-ur-jenz). If your immune system reacts to an allergen and you have symptoms, you may be allergic to it.

Common allergens include:

  • dust mites (tiny insects that live in dust)
  • animal hair or dander (skin flakes) from dogs, cats, or other animals
  • grass, flower, and tree pollen (the fine dust from plants)
  • mold and mildew (small living things that grow in damp places)
  • foods such as cow’s milk, eggs, wheat, soy, peanuts, tree nuts, fish, shellfish, or sesame seeds
  • latex (a kind of rubber used to make gloves and some balloons)

What Are the Signs & Symptoms of Allergies?

Allergy symptoms depend on what type of allergy a kid has. Most allergies can cause:

Food allergies can also cause:

  • stomach cramps
  • vomiting
  • diarrhea

Some allergies are seasonal, which means you’ll only have symptoms during certain times of the year. Pollen allergies tend to be worse in the spring, summer, and early fall. With other allergies, you may have symptoms whenever you have contact with the allergen.

While most allergies are mild, some can be very serious and cause a reaction called anaphylaxis (say: an-uh-fuh-LAK-sis). A person with anaphylaxis might have trouble breathing, an itchy or tight throat, or feel like throwing up. Anyone with anaphylaxis needs to get emergency help right away.

Why Do Some Kids Get Allergies?

Doctors aren’t sure why some kids get allergies, and why some things are more likely to cause allergies than others. Some allergies run in families, so if a parent has had allergies, a kid might too.

Allergies are most common in kids, and many kids outgrow them by the time they’re adults. But adults can have allergies too and sometimes people don't get allergies until later in life.

How Do I Find Out if I Have Allergies?

To find out if you have allergies, your doctor will ask about your health, the animals and plants in your home, and the foods you eat. This will help them figure out if you might be allergic to any of these things.

Your doctor also might send you to an allergist (say: AL-ur-jist), a doctor who helps people who have allergies. The allergist may give you a scratch test to see if a tiny bit of an allergen will cause a reaction on your skin. You'll feel a quick pinch when the doctor makes the scratches, and they’ll become swollen and itchy if you’re allergic. Some doctors also might test a kid's blood to look for signs of an allergic reaction.

How Are Allergies Treated?

Your doctor will probably suggest ways to stay away from the allergen or give you medicine. Allergy medicine can be pills or liquids to swallow or sprays for your nose. If your allergies aren't too bad, or if you can avoid the allergen completely, you might not need medicine.

If your symptoms don't get better by trying to stay away from allergens and taking medicine, an allergist might suggest allergy shots. These make your immune system less sensitive to the allergens.

Shots and most medicine don't help with food allergies, though. So kids with a food allergy usually need to learn how to avoid the food they're allergic to. One way to figure that out is to read food labels. Ask your parent or doctor if you need help learning to do this.

You might not always be able to control your allergies, but you can do yourself a favor by learning to avoid anything that causes your allergy symptoms.

Reviewed by: Melanie L. Pitone, MD
Date Reviewed: May 1, 2024

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