A food allergy is a condition in which certain foods trigger an abnormal immune response ( 2 ).

It’s caused by your immune system wrongly recognizing some of the proteins in a food as harmful. Your body then launches a range of protective measures, including releasing chemicals like histamine, which causes inflammation.

For people who have a food allergy, even exposure to very small amounts of the problem food can cause an allergic reaction.

Symptoms can occur anywhere from a few minutes after exposure to a few hours later, and they may include some of the following:

Swelling of the tongue, mouth or face

Difficulty breathing

Low blood pressure

Vomiting

Diarrhea

Hives

Itchy rash

In more severe cases, a food allergy can cause anaphylaxis. Symptoms, which can come on very quickly, include an itchy rash, swelling of the throat or tongue, shortness of breath and low blood pressure. Some cases can be fatal ( 3 ).

Many food intolerances are often mistaken for food allergies.

However, food intolerances never involve the immune system. This means that while they can severely impact your quality of life, they are not life threatening.

True food allergies can be divided into two main types: IgE antibody or non-IgE antibody. Antibodies are a type of blood protein used by your immune system to recognize and fight infection ( 4 ).

In an IgE food allergy, the IgE antibody is released by your immune system. In a non-IgE food allergy, IgE antibodies aren’t released, and other parts of the immune system are used to fight the perceived threat.

Here are the eight most common food allergies.