Physical reactions to certain foods are common, but most are caused by a food intolerance rather than a food allergy. A food intolerance can cause some of the same signs and symptoms as a food allergy, so people often confuse the two.
A true food allergy affects the immune system. Even small amounts of the offending food can trigger a range of symptoms, which can be severe or life-threatening. In contrast, a food intolerance often affects only the digestive system and causes less serious symptoms.
If you have a food intolerance, you may be able to eat small amounts of the offending food without trouble. You may also be able to prevent a reaction. For example, if you have lactose intolerance, you may be able to drink lactose-free milk or take lactase enzyme pills (Lactaid) to aid digestion.
Causes of food intolerance include:
- Absence of an enzyme needed to fully digest a food. Lactose intolerance is a common example.
- Irritable bowel syndrome. This chronic condition can cause cramping, constipation and diarrhea.
- Sensitivity to food additives. For example, sulfites used to preserve dried fruit, canned goods and wine can trigger asthma attacks in people who are sensitive to food additives.
What about celiac disease?
This chronic digestive condition is triggered by eating gluten, a protein found in wheat and other grains. Celiac disease has some features of a true food allergy because it involves the immune system. Symptoms often include gastrointestinal issues as well as those unrelated to the digestive system, such as joint pain and headaches. However, people with celiac disease are not at risk of anaphylaxis.
If you have a reaction after eating a particular food, see your doctor to determine whether you have a food intolerance or a food allergy.
If you have a food allergy, you may be at risk of a life-threatening allergic reaction (anaphylaxis) — even if past reactions have been mild. Learn how to recognize a severe allergic reaction and know what to do if one occurs. You may need to carry an emergency epinephrine shot (Adrenaclick, Auvi-Q, EpiPen) for emergency self-treatment.
If you have a food intolerance, your doctor may recommend steps to aid digestion of certain foods or to treat the underlying condition causing your reaction.
April 21, 2022
From Mayo Clinic to your inbox
Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health.
ErrorEmail field is required
ErrorInclude a valid email address
To provide you with the most relevant and helpful information, and understand which
information is beneficial, we may combine your email and website usage information with
other information we have about you. If you are a Mayo Clinic patient, this could
include protected health information. If we combine this information with your protected
health information, we will treat all of that information as protected health
information and will only use or disclose that information as set forth in our notice of
privacy practices. You may opt-out of email communications at any time by clicking on
the unsubscribe link in the e-mail.
Thank you for subscribing
Our Housecall e-newsletter will keep you up-to-date on the latest health information.
Sorry something went wrong with your subscription
Please, try again in a couple of minutes
See more Expert Answers
- Food intolerance versus food allergy. American Academy of Allergy, Asthma and Immunology. https://www.aaaai.org/Tools-for-the-Public/Conditions-Library/Allergies/Food-Intolerance. Accessed March 9, 2022.
- Commins SP. Food intolerance and food allergy in adults: An overview. https://www.uptodate.com/contents/search. Accessed March 9, 2022.
- Food intolerance. National Health Service. https://www.nhs.uk/conditions/food-intolerance/. Accessed March 9, 2022.
- Alkalay MJ. Nutrition in patients with lactose malabsorption, celiac disease, and related disorders. Nutrients. 2022; doi:10.3390/nu14010002.