Food Allergy: Common Triggers, Symptoms, Anaphylaxis and Treatment

A food allergy is an abnormal immune system reaction to certain foods. Normally the immune system protects you from germs; with a food allergy, it mistakenly treats a food as harmful. Most reactions are mild, but some are serious or even life-threatening.

A food intolerance is different. It also causes symptoms after eating a food, but usually just digestive ones such as bloating and gas — and it is not an immune reaction.

The usual culprits

Most food allergies are caused by:

People can be allergic to more than one food.

Who gets them

Both children and adults can have food allergies. Some children outgrow them, and some people develop them as adults. The risk is higher if you:

• have eczema, an immune-related skin disease causing inflammation, redness and irritation
• have asthma or other allergies, such as hay fever
• have certain genes, or family members with allergies, asthma or eczema

Symptoms

Symptoms usually begin within a few minutes to two hours of eating the food. They vary from person to person — and from one time to the next, sometimes depending on how much was eaten:

• hives, flushed skin or rash
• tingling or itching in the mouth
• swelling of the face, tongue or lips
• vomiting, diarrhea or belly cramps
• coughing or wheezing
• dizziness or lightheadedness
• swelling of the throat and vocal cords
• trouble breathing

Anaphylaxis: an emergency

Rarely, a food allergy causes anaphylaxis, a life-threatening reaction that may start mild and quickly worsen, leading to:

• narrowed airways in the lungs
• severe trouble breathing from throat swelling
• a severe drop in blood pressure — anaphylactic shock
• loss of consciousness

Call 911 if someone has symptoms of anaphylaxis.

Diagnosis

A health care provider will ask about your symptoms and your family and medical history, including other allergies, will likely examine you, and will do allergy testing — skin tests, blood tests, an elimination diet, and/or an oral food challenge, the most accurate test.

Treatment

There is no cure. The only way to prevent a reaction is to avoid the food. Medicines can help:

• antihistamines and corticosteroids to ease symptoms
• medicines to reduce allergic reactions, including severe ones
• epinephrine to treat anaphylaxis, often prescribed as an auto-injector. If you have one, learn how to use it and carry it at all times.

A medical alert bracelet naming your allergy is also a good idea.

Sources

Based on "Food Allergy," MedlinePlus, U.S. National Library of Medicine; a work of the United States government in the public domain.