Food Allergies Overview
A food allergy happens when your immune system reacts to certain proteins in a food. Reactions range from mild hives and lip swelling to anaphylaxis, which can be life-threatening (FDA). In 2021, about 6.2% of U.S. adults had a diagnosed food allergy (CDC).
Food allergies are different from seasonal allergies, which are caused by airborne pollen and mold. See our comparison of seasonal vs. food allergies.
How Do Food Allergies Occur In Your Body?
Food allergies involve two parts of your immune system. One is immunoglobulin E (IgE), a protein type that is known as an antibody that moves through your blood. The other part is mast cells, the cells present in all of your body tissues, but primarily they are in places like your nose, throat, lungs, skin, and digestive tract.
When a particular food enters your body, the body produces many antibodies to fight it off i.e., IgE. The IgE fights the allergen i.e., the allergic food, and then attaches itself to the mast cells. But, the first time the allergen entered your body, it has prepared the body for food allergy. And the next time you intake the same food, the body overreacts to it, and you will witness the symptoms, and hence food allergy has occurred.
Most Common Types of Food Allergies
More than 160 foods have been identified as causing food allergies, but in the U.S. nine are recognized by law as major food allergens and must be clearly labeled on packaged foods (FDA).
The 9 major food allergens in the U.S. are (FDA):
- Milk
- Eggs
- Fish
- Crustacean shellfish (such as crab, lobster and shrimp)
- Tree nuts
- Peanuts
- Wheat
- Soybeans
- Sesame (added as the 9th major allergen on January 1, 2023)
Other foods and additives, such as sulfites, can also cause reactions in sensitive people, and sulfites must be declared on labels at certain levels (FDA). Children are more likely to outgrow milk and egg allergies than peanut, tree nut or fish allergies.
Symptoms
Reactions vary from person to person and from one reaction to the next. Symptoms typically appear within a few minutes to a few hours after eating the food (FDA). They can include:
Most common food allergy symptoms are:
- sneezing, runny or blocked nose
- itchy, red or watery eyes
- wheezing
- chest tightness, shortness of breath and dry cough
- raised red rashes on the skin
- swollen lips, tongue, eyes or face
- tummy pain, feeling sick, dizziness, vomiting or diarrhea
- dry, red and cracked skin
Food allergies can start at any age. Many begin in childhood, and some children outgrow them, but adults can develop new food allergies too. No one can predict how severe the next reaction will be.
How Food Allergies Are Tested
Diagnosis starts with your history: what you ate, how soon symptoms began, and what they were. An allergist may then use a skin prick test or a blood (IgE) test for the specific food you reacted to. A positive result alone doesn’t make a diagnosis, and broad panels testing many foods at once aren’t recommended (NIAID).
If results are unclear, an oral food challenge under medical supervision is considered the most accurate test (ACAAI). Avoid IgG “food sensitivity” panels: the AAAAI recommends against using them to diagnose food allergies or intolerances (AAAAI). See our full allergy testing guide.
Adult-Onset Food Allergies
Food allergy symptoms are most common in babies and children, but they can appear at any age (ACAAI). The most common food allergens in adults are fruit and vegetable pollen (oral allergy syndrome), peanuts and tree nuts, and fish and shellfish (ACAAI). If you develop new symptoms after eating a food as an adult, see an allergist rather than testing it again on your own.
Treatment
Referring to an allergist is quite essential to confirm the diagnosis of a doubted food allergy. Patients should prevent the food in the issue until complete examination. Before treatment, diagnostic tests are crucial, which are taken by the allergists. Moreover, The SPT is a rapid, safe, and susceptible method for diagnosing suspected IgE-mediated food allergy.
An oral food challenge is also applied if the results of the SPT are not precise. In this method, the allergic person is given the trigger food gradually with complete medical assistance.
An allergist may also use an elimination diet or a food and symptom diary to help pinpoint trigger foods. Never try to test a food on your own if you’ve had a severe reaction.
There is still no cure for food allergy, and strict avoidance of trigger foods remains the foundation of care. But treatment has advanced: Palforzia is an FDA-approved oral immunotherapy for peanut allergy in ages 4 to 17, and in February 2024 the FDA approved Xolair (omalizumab) to reduce reactions after accidental exposure to one or more foods in people 1 year and older. Neither replaces avoidance or emergency epinephrine, which is the treatment for anaphylaxis (FDA).
Conclusion
Food allergies can appear at any age and currently can’t be cured. Read labels carefully, carry epinephrine if prescribed, and work with an allergist, who can tell you whether newer treatments are right for you. If you have a reaction, stop eating the food and use epinephrine if needed, then seek medical care (FDA).
Written by: Madiha Ather Hashmi (April 24, 2020)
This article is for general education and is not medical advice. Talk with your doctor or pharmacist about your symptoms and before starting, stopping, or combining any medicine.
Food Allergy FAQs
What are the 9 major food allergens?
Milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame (FDA).
Can food allergies be cured?
Not yet. Avoidance is still required, though Palforzia and Xolair can reduce reactions after accidental exposure in certain patients (FDA).
How soon do food allergy symptoms start?
Usually within a few minutes to a few hours after eating (FDA).
Are “may contain” labels required?
No. Advisory statements like “may contain” are voluntary, so contact the manufacturer if unsure (FDA).
Sources
- U.S. Food and Drug Administration. “Food Allergies.”
https://www.fda.gov/food/nutrition-food-labeling-and-critical-foods/food-allergies - U.S. Food and Drug Administration (Feb. 2024). “FDA Approves First Medication to Help Reduce Allergic Reactions to Multiple Foods After Accidental Exposure.”
https://www.fda.gov/news-events/press-announcements/fda-approves-first-medication-help-reduce-allergic-reactions-multiple-foods-after-accidental - CDC National Center for Health Statistics (2023). NCHS Data Brief 460.
https://www.cdc.gov/nchs/products/databriefs/db460.htm - National Institute of Allergy and Infectious Diseases. “Food Allergy Diagnosis.”
https://www.niaid.nih.gov/diseases-conditions/food-allergy-diagnosis - American College of Allergy, Asthma and Immunology. “Food Allergy.”
https://acaai.org/allergies/allergic-conditions/food/ - American Academy of Allergy, Asthma & Immunology. “The Myth of IgG Food Panel Testing.”
https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/igg-food-test
Looking for more allergy types? Find a full list of other allergy causes here.