Diseases & Conditions

Food allergy

Food allergy is an immune system reaction that occurs soon after eating a certain food. Even a tiny amount of the allergy-causing food can trigger signs and symptoms such as digestive problems, hives or swollen airways. In some people, a food allergy can cause severe symptoms or even a life-threatening reaction known as anaphylaxis.

Food allergy affects an estimated 6 to 8 percent of children under age 3, and about 4 percent of adults. While there's no cure, some children outgrow their food allergy as they get older. It's easy to confuse a food allergy with a much more common reaction known as food intolerance. While bothersome, food intolerance is a less serious condition that does not involve the immune system.

Complications of food allergy can include:

• Anaphylaxis, a life-threatening allergic reaction.
• Atopic dermatitis (eczema). About one in three people with atopic dermatitis also have a food allergy.
• Migraines. Histamines, released by your immune system during an allergic reaction, have been shown to trigger migraines in some people.

While some people think food allergies are linked to childhood hyperactivity and to arthritis, there's no evidence to support this.

The only way to avoid an allergic reaction is to avoid the foods that cause signs and symptoms. However, despite your best efforts, you may come into contact with a food that causes a reaction.

For a minor allergic reaction, over-the-counter or prescribed antihistamines may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve itching or hives. However, antihistamines can't treat a severe allergic reaction.

For a severe allergic reaction, you may need an emergency injection of epinephrine and a trip to the emergency room. Many people with allergies carry an autoinjector (EpiPen, EpiPen Jr or Twinject). This device is a combined syringe and concealed needle that injects a single dose of medication when pressed against your thigh. If your doctor has prescribed an epinephrine autoinjector:

• Carry it with you at all times. It may be a good idea to keep an extra autoinjector in your car or in your desk at work as well.
• Always be sure to replace epinephrine before its expiration date, or it may not work properly.
• Be sure you know how to use the autoinjector. Also, make sure the people closest to you know how to administer the drug — if they're with you in an anaphylactic emergency, they could save your life.

While there's ongoing research to find better treatments to reduce food allergy symptoms and prevent allergy attacks, there isn't any proven treatment that can prevent or completely relieve symptoms. Unfortunately allergy shots (immunotherapy), a series of injections used to reduce the effect of other allergies such as hay fever, aren't effective for treating food allergies.

The key treatment is to do your best to avoid the food in question, and work with your doctor to identify what steps you can take to relieve your symptoms and how to spot and respond to a severe reaction.