Achoo! Every time you go near your best friend's cat, your eyes water and you start sneezing up a storm. And every spring and fall, your dad gets a runny nose when he takes you for hikes in the woods.

What's going on? Well, you and your dad may have allergies.

Chain Reaction

An allergy (say: al-ur-jee) is your immune system's reaction to certain plants, animals, foods, insect bites, or other things. Your immune system protects you from diseases by fighting germs like bacteria and viruses, but when you have allergies, it overreacts and tries to "fight" ordinary things like grass, pollen, or certain foods. This causes the sneezing, itching, and other reactions that you get with allergies.

The substances that cause allergies (grass, pollen, foods, pet byproducts, insects, etc.) are called allergens (say: al-ur-jenz). When your immune (say: ih-myoon) system reacts to one of these allergens and you have symptoms, you are allergic to it.

What Causes the Sneezing and Wheezing?

You can be allergic to many things. Common allergens include:

• dust mites (tiny insects that live in dust)
• a protein found in the dander (dry skin), saliva (spit), urine (pee), or other things from some 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 milk, wheat, soy, eggs, nuts, seafood, and legumes (say: leh-gyooms), which include peas, beans, and peanuts
• latex (stretchy stuff that some of the gloves doctors and dentists use are made of)

Symptoms

Some of these allergens cause sneezing, a runny nose, itchy eyes and ears, and a sore throat. Other items on the list, such as foods, may cause hives (a red, bumpy, itchy skin rash), a stuffy nose, stomach cramps, vomiting, or diarrhea.

Less often, allergens can cause breathing problems like wheezing and shortness of breath (asthma). Some allergens, such as foods, are a problem all year long. But others might bother people only during certain seasons. For instance, you might be allergic to pollen from trees, which is present in the air only in the spring.

Why Do Some Kids Get Allergies?

People may be born with a genetic (say: juh-neh-tik) tendency to have allergies, which means they are more likely to get them than other people are. Many allergies are hereditary (say: huh-reh-dih-tare-ee) — passed to kids in the genes they get from their parents — so you have a better chance of having allergies if your mom or dad or other people in your family have them.

People can develop allergies when they are babies, children, teens, or adults, although allergies often decrease in older people.

Many people outgrow food allergies. Other allergies can last your whole life, although they may be less severe and more severe at different points in your life.

Colds vs. Allergies

Sometimes it's difficult to tell the difference between a cold and an allergy because the symptoms can be similar. If your cold symptoms last more than 2 weeks, you probably have an allergy instead of a cold.

There are other differences between colds and allergies you can look for. With allergies, your nose and eyes itch. Colds don't itch. The mucus, the stuff that comes from your nose or that you cough up, is different, too. With allergies, it's clear like water. With a cold, it's usually yellowish and thick.

How Do I Find Out if I Have Allergies?

If you sneeze and itch a lot, wheeze, or often get sick after eating a certain food, your doctor may want to check you for allergies. He or she will ask you a lot of questions about your health, about the animals and plants in your home, and about the foods you eat. Your answers will provide clues about what you might be allergic to, and your doctor may ask you to stay away from a pet or stop eating a certain food to see if your symptoms go away.

Your doctor may send you to an allergist (say: al-ur-jist), a special doctor who helps people who have allergies. An 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 scratch or scratches. If you're allergic, one or more spots will become bumpy, itchy, and red — like a mosquito bite.

Some doctors also might test a kid's blood to look for IgE, a substance called an antibody (say: an-tie-bah-dee) that signals an allergic reaction. If you have large amounts of this antibody in your blood, you are probably allergic to the allergen.

Taking Control

Your doctor will probably suggest ways to stay away from the allergen or prescribe a medicine for you to try. Allergy medicine can be pills, liquids, or even sprays for your nose. If your allergies aren't too bad or if you can avoid the allergen completely, you might not need to take medicine — staying away from the allergen might be enough to control your allergy.

If your symptoms don't get better by staying away from allergens and taking medicines, an allergist might recommend allergy shots. These shots make your immune system less sensitive to the allergens and can make your symptoms better.

Unfortunately, shots and most medicines don't help with food allergies. People with food allergies have to learn to avoid any foods that have the ingredients they're allergic to. Your parents and your doctor can help you read the ingredients on food labels. Luckily, many kids outgrow allergies to milk, eggs, wheat, and soy. But allergies to peanuts, tree nuts, and seafood usually last.

Fighting on the Allergy Front

You may not be able to control your allergies completely, but you can do yourself a favor by avoiding anything that causes your allergy symptoms.

Pets. If you are allergic to an animal, you might have to find a new home for your pet. If you can't do that, it can help to keep pets out of your bedroom, have someone bathe them once a week, or have the animal live outside. You'll also want to avoid pets at other people's homes.

Dust mites. If dust mites are your trouble, your mom or dad can use special covers for your bed and wash your sheets and blankets in very hot water to get rid of them. Keeping your room neat and clean also will help. Store stuffed animals or other stuff that attracts dust somewhere other than your room.

Food allergies. If you have food allergies, always read food labels to check the ingredients and learn the different names for the food allergen. If you're not sure about a food, don't eat it. Instead, ask a grownup if it's safe. Your mom or dad can help teach you which foods and ingredients you should avoid.

Also, your parents can help you pack safe snacks for occasions away from home when everyone else might be having something you can't, such as peanut butter ice cream. Then, instead of feeling left out, you can snack along with your friends — without risking an allergy attack and, even worse, having to go home early!

Reviewed by: Steven Dowshen, MD
Date reviewed: February 2012
Originally reviewed by: Stephen J. McGeady, MD