Nearly any food can cause an allergy, but the most common food allergens are:

• peanuts

• tree nuts

• milk

• eggs

• shellfish

• fish

• wheat

• soy

• some fruits and vegetables

This is the most common type of food allergy. It occurs when the immune system produces the antibody immunoglobulin E (IgE). Symptoms happen within a few minutes after eating the allergen. Anaphylaxis is more common with this type of reaction.

Symptoms of IgE-mediated food allergy can include:

• Hives

• Swelling, especially of the face, mouth or throat

• Itching or tingling inside the mouth

• Trouble swallowing

• Dizziness

• Nausea or vomiting

• Wheezing or shortness of breath

• Diarrhea

• Abdominal pain

• Itchy eyes

• Sneezing

Anaphylaxis is a severe allergic reaction. This is an emergency that can happen suddenly and worsen rapidly. If you see someone in anaphylaxis, give epinephrine if trained to do so, and call an ambulance immediately.

In addition to the symptoms above, a person in anaphylaxis may have:

• Difficulty breathing, swallowing or speaking

• Chest tightness

• Tongue swelling

• Dizziness or feeling faint

• Collapse

In this type of allergy, immunoglobulin E is not involved. Instead, other immune cells cause the reaction. After eating, it can take several hours or even days for the reaction to develop.

Symptoms of a non-IgE-mediated food allergy include:

• Red, itchy skin (but not raised hives)

• Eczema

• Vomiting

• Diarrhea

• Constipation

• Abdominal cramps

• Colic in babies

In a mixed reaction, a person experiences symptoms from both immunoglobulin E (IgE) and other immune cells.