When you have a food allergy, your body thinks certain foods are trying to harm you. Your body fights back by setting off an allergic reaction. In most cases, the symptoms are mild—a rash, a stuffy nose, or an upset stomach. A mild reaction is no fun, but it is not dangerous. A serious reaction can be deadly. But quick treatment can stop a dangerous reaction.
Allergies tend to run in families. You are more likely to have a food allergy if other people in your family have allergies like hay fever, asthma, or eczema.
Food allergies are more common in children than adults. About 7 out of 100 kids have them. Only about 3 to 4 out of 100 adults do.1 Children often outgrow their food allergies. But if you have a food allergy as an adult, you will most likely have it for life.
What are the symptoms?
Food allergies can cause many different symptoms. They can range from mild to serious. If you eat a food you are allergic to:
- Your mouth may tingle, and your lips may swell.
- You may have cramps, an upset stomach, or diarrhea.
- You may have itchy skin with red, raised bumps called hives.
- You may have a stuffy nose, wheeze, or be short of breath.
- You may feel dizzy or lightheaded.
Kids usually have the same symptoms as adults. But sometimes a small child just cries a lot, vomits, has diarrhea, or does not grow as expected. If your child has these symptoms, see your doctor.
Some people have symptoms after eating even a tiny bit of a problem food. As a rule, the sooner the reaction begins, the worse it will be.
The most severe reaction is called anaphylaxis (say “ANN-uh-fuh-LAK-suss”). It affects your whole body. Anaphylaxis usually starts within an hour after you eat the food, and the symptoms can come back 1 to 2 hours later. If you have anaphylaxis:
- Your throat and tongue may swell quickly.
- You may suddenly start wheezing or have trouble breathing.
- You may feel sick to your stomach or vomit.
- You may feel faint or pass out.
What foods most often cause a food allergy?
A few foods cause most allergies. A food that causes an allergy is called a food allergen. Usually it is the protein in a food that causes the problem.
Eggs, milk, peanuts, wheat, soy, and fish cause most problems in children. Most kids outgrow allergies to milk, wheat, eggs, and soy by the time they are 5. But kids rarely outgrow an allergy to peanuts or fish.
Peanuts, tree nuts (like walnuts or almonds), fish, and shellfish cause most problems in adults.
If you are allergic to one food, you may also be allergic to other foods like it. So if you are allergic to peanuts, you may also be allergic to soybeans or peas.
How is a food allergy diagnosed?
Your doctor will ask questions about your medical history and do a physical exam. Your doctor will also ask what symptoms you have. He or she may want you to write down everything you eat and any reactions you have.
If your doctor thinks you could have a serious food allergy, you may have a skin test. The doctor will put a little bit of liquid on your skin and then prick your skin. The liquid has some of the possible food allergen in it. If your skin swells up like a mosquito bite, your doctor knows you are allergic to that food. Your doctor may also do blood tests to look for the chemicals in your blood that cause an allergic reaction.
