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 causes an immune system reaction that affects
numerous organs in the body. It can cause a range of symptoms.
In some cases, an allergic reaction to a food can be severe or life-
threatening. In contrast, food intolerance symptoms are generally
less serious and often limited to digestive problems.
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.
Food poisoning. Toxins such as bacteria in spoiled food can
cause severe digestive symptoms.
Sensitivity to food additives. For example, sulfites used to
preserve dried fruit, canned goods and wine can trigger
asthma attacks in sensitive people.
Recurring stress or psychological factors. Sometimes the
mere thought of a food may make you sick. The reason is not
Celiac disease. Celiac disease has some features of a true
food allergy because it involves the immune system. However,
symptoms are mostly gastrointestinal, and people with celiac
disease are not at risk of anaphylaxis. This chronic digestive
condition is triggered by eating gluten, a protein found in
wheat and other grains.
If you have a reaction after eating a particular food, see your
doctor to determine whether you have a food intolerance or a food
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 (EpiPen, Auvi-Q, others) for emergency self-
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.