Food allergy

Basic Information


Food allergy is an overreaction of the immune system to certain foods or substances that are otherwise harmless. These adverse reactions may be inborn or an acquired biochemical defect. Symptoms may occur within minutes or up to 2 hours after ingesting the food. In some instances, the symptoms may not appear until a day or two later.

Frequent signs and symptoms

  • Diarrhea (common).
  • Abdominal pain (common).
  • Flatulence and bloating (common).
  • Skin rash.
  • Hives.
  • Itching.
  • Face swelling (especially lips).
  • Swelling of hands and feet.
  • Hay fever.
  • Nausea and vomiting.
  • Asthma.
  • Cough.
  • Migraine headache.
  • Fainting or near-fainting.

What causes Food allergy?

Any food or swallowed substance can cause allergic reactions. Foods most often involved are cow's milk, egg whites, wheat, soybeans, peanut, fish, tree nuts (walnut and pecan), shellfish, melons, sesame seeds, sunflower seeds and chocolate.

Risk increases with

  • People who have other allergy problems.
  • Having family members with a history of food allergy.

Preventive measures

  • Identify responsible foods and avoid them.
  • Breast-fed infants who are started on solid foods late tend to have fewer allergies.

Expected outcomes

  • Infants usually will outgrow food hypersensitivity by 2-4 years of age.
  • Adults with food hypersensitivity (particularly to milk, fish, shellfish or nuts) are more likely to maintain their allergy for many years.

Possible complications

  • Anaphylaxis (difficulty in breathing, heart irregularities, blood pressure drop).
  • Hive-like reaction.
  • Bronchial asthma.
  • Bowel inflammation.
  • Eczema-like lesions.

Food allergy treatment

General measures

  • Elimination of the suspected foods in your diet for 2 weeks (or until all symptoms disappear) and then eating the foods again one by one to see if the symptoms return.
  • Skin tests may occasionally identify the offending food, but frequently they give results indicating that you are allergic to certain foods when you aren't.
  • Patients with severe allergy hypersensitivity to a food should be extra cautious in their avoidance of that food.
  • Carry a kit with an adrenaline-containing syringe in case the offending food is eaten accidentally and a subsequent immediate reaction develops.
  • Consider wearing a medical alert bracelet or neck pendant that indicates the specific allergy problem.


No medication is available to treat food allergy, but medications may be prescribed to relieve some of the symptoms.


No restrictions.


Avoidance of the offending food, or limiting yourself to small amounts of it. Read food labels carefully.

Notify your physician if

  • You or a family member has mild to moderate symptoms of a food allergy.
  • Someone appears to have a severe reaction after eating. Call for emergency help immediately.

Last updated 14 June 2015


© All rights reserved. Registration is not required to view the information on the site.