Alcohol intolerance can cause immediate, unpleasant reactions after you drink alcohol. The most common signs and symptoms of alcohol intolerance are stuffy nose and skin flushing. Alcohol intolerance is caused by a genetic condition in which the body is unable to break down alcohol efficiently. The only way to prevent alcohol intolerance reactions is to avoid alcohol.
Alcohol intolerance isn't an allergy. However, in some cases, what seems to be alcohol intolerance may be your reaction to something in an alcoholic beverage — such as chemicals, grains or preservatives. Combining alcohol with certain medications also can cause reactions.
In rare instances, an unpleasant reaction to alcohol can be a sign of a serious underlying health problem that requires diagnosis and treatment.