What are food allergies?

When the body’s immune system reacts abnormally to something you eat or drink, it’s known as a food allergy.

According to Food Allergy Research and Education (FARE), it’s estimated that 15 million Americans have food allergies. Children are more likely. Approximately 1 in every 13 children in the United States lives with food allergies.

A food allergy may affect the skin, gastrointestinal tract, or respiratory or cardiovascular systems. Many types of foods can be allergens, but certain foods are much more likely than others to trigger an allergic reaction.

According to FARE, the following 8 foods are responsible for 90 percent of all food allergies:

Symptoms of food allergies may range from mild to severe. They may come on suddenly or develop over several hours.

A person’s immune system may react to a small amount of the allergen, so food allergies can be particularly dangerous and life-threatening, especially if breathing is affected. Because food allergies can affect breathing, people with asthma are at an increased risk of a fatal allergic reaction to food.

Mild symptoms related to a food allergy may include:

  • sneezing
  • stuffy or runny nose
  • itchy, watery eyes
  • swelling
  • rash
  • stomach cramps
  • diarrhea

Symptoms of a severe allergic reaction (called anaphylaxis) to food are:

  • difficulty breathing, including wheezing
  • swelling of the lips, tongue, or throat
  • hives (an itchy, blotchy, and raised rash)
  • dizziness or faintness
  • nausea or vomiting

Milk allergies have been studied more than any other food allergy. A milk allergy is a reaction to whey or casein, the proteins found in cow’s milk. It’s not the same as lactose intolerance.

Children with milk allergies are much more likely to develop allergic reactions to other foods, including eggs, soy, and peanuts. Most children with milk allergies also develop one or more other atopic diseases, such as asthma, allergic rhinitis, or eczema.

Egg allergies occur most often in children and usually resolve at a very young age. However some people may remain allergic to eggs for their entire lives.

A person may be allergic to a certain protein in either the yolk or the egg white. A person with an allergy to egg yolks may be able to tolerate egg whites and vice versa. Some people are allergic to both.

Children with peanut allergies rarely grow out of their sensitivity to peanuts, so a peanut allergy is usually a lifelong disorder. Because of this, peanut allergies are particularly serious. Accidental exposure can occur at any time during a person’s life.

Though rare, a peanut allergy may result in anaphylaxis. This is a severe allergic reaction that can restrict breathing or cause cardiac arrest. Anaphylaxis requires immediate medical attention in the form of a shot of epinephrine (EpiPen). You should be watched for several hours after the shot to make sure symptoms don’t return.

Less is known about soy and wheat allergies than the more common allergies discussed above. Likewise, little is known about fish, shellfish, and tree nut allergies, except that they’re generally lifelong disorders.

The way food allergies are diagnosed usually depends on the severity of symptoms.

If your symptoms are mild, a doctor may recommend keeping a food diary to record all of the foods you eat or drink to pinpoint the culprit. Another way to diagnose a mild food allergy is to remove certain foods from the diet and then slowly reintroduce them to find out if symptoms return.

In the case of more severe allergies, skin or blood tests can identify egg, milk, nut, and shellfish allergies.

As with other types of allergies, avoidance is often the best medicine. Anyone with a food allergy should be careful when purchasing food at a supermarket or restaurant to make sure there are no traces of the allergen.

Mild symptoms may not require any treatment at all, or a simple over-the-counter antihistamine may resolve the symptoms.

For more serious allergic reactions, a doctor may prescribe steroid medications. Steroids may have serious side effects and shouldn’t be used for more than a few days at a time.