Health Topic

Food Allergy

Food allergy is an abnormal response triggered by your body's immune system. The reaction may be mild or severe (anaphylaxis). Learn more.

Reviewed Reviewed by a registered pharmacistGeneral information

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Food Allergy

A food allergy is an abnormal immune system reaction to certain foods. Your immune system normally protects you from germs. But if you have a food allergy, your immune system mistakenly reacts to certain foods as if they were harmful. This reaction is usually mild. But in some cases, it can be serious or even life-threatening.

A food intolerance is different than a food allergy. If you have a food intolerance, you also have symptoms when you eat that food. But these are typically just digestive symptoms such as bloating and gas. Also, an intolerance is not an immune system reaction.

Most food allergies are caused by:

  • Cow's milk
  • Chicken eggs
  • Crustacean shellfish, such as shrimp, crab, lobster, and crayfish
  • Fish
  • Peanuts
  • Sesame
  • Soy
  • Tree nuts, such as almonds, walnuts, pecans
  • Wheat

People with a food allergy may be allergic to more than one type of food.

Both children and adults can have food allergies. Some children will outgrow their food allergies. And sometimes people can develop food allergies as adult.

Certain factors can make you more likely to have a food allergy. They include:

  • Having eczema, a disease that causes inflammation, redness, and irritation of the skin. Your immune system also plays a role in eczema.
  • Having asthma or other allergies, such as hay fever.
  • Your genes. Certain genes may influence the development of food allergies. And you are more likely to have food allergies if someone in your family has allergies, asthma, or eczema.

If you are allergic to a food you have eaten, you may have a variety of symptoms. These symptoms are not always the same for every person. And the symptoms that you get each time you eat the food may not always be the same. For example, your symptoms may sometimes depend on how much of the food you ate.

Food allergy symptoms usually start within a few minutes to two hours after you eat that food. They may include:

  • Hives
  • Flushed skin or rash
  • Tingling or itchy sensation in the mouth
  • Face, tongue, or lip swelling
  • Vomiting and/or diarrhea
  • Abdominal (belly) cramps
  • Coughing or wheezing
  • Dizziness and/or lightheadedness
  • Swelling of the throat and vocal cords
  • Trouble breathing

In rare cases, a food allergy can cause a life-threatening reaction called anaphylaxis. It may start out with some milder symptoms, but then it becomes more serious. It can lead to:

  • Narrowed airways in the lungs
  • Severe trouble breathing because of swelling in the throat
  • Severe lowering of blood pressure and shock ("anaphylactic shock")
  • Loss of consciousness

This is a medical emergency. Call 911 if someone is having the symptoms of anaphylaxis.

To find out if you have a food allergy, your health care provider will

  • Ask about your symptoms, family health history, and medical history, including other allergies.
  • Likely do a physical exam.
  • Do food allergy testing. This could involve skin testing, blood testing, a food elimination diet, and/or an oral food challenge test. An oral food challenge test is the most accurate food allergy test.

There is no cure for food allergies. The only way to prevent a reaction is to avoid eating the food that you are allergic to.

There are medicines for people with food allergies. They include:

  • Medicines to reduce food allergy symptoms, including antihistamines and corticosteroids.
  • Medicines to reduce allergic reactions, including severe reactions.
  • Epinephrine, a medicine to treat anaphylaxis. Your provider may give you a prescription for an epinephrine auto-injector. It is a device used to inject epinephrine when someone is having symptoms of anaphylaxis. If you have been prescribed one, it's important to learn how to use it and to carry it with you at all times.

If you have a food allergy, it's a good idea to have a medical alert bracelet that says what your allergy is.

It sits within Immune System and Food and Nutrition.

The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Food Allergy

748 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

Start Here

Diagnosis and Tests

Treatments and Therapies

Living With

Related Issues

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Food Hypersensitivity. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Food Allergy, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.