Alcohol intolerance is actually a metabolic disorder in which consumption of even moderate amounts of alcohol causes allergy and unpleasant reactions in the body due to the unavailability of the enzyme that breakdown and metabolizes alcohol. It is very commonly seen in Asian descents. Alcohol intolerance shouldn’t be confused with other alcohol allergies which can be due to the preservatives present in the alcohol.
It is caused due to a genetic deficiency of the two enzyme alcohol dehydrogenase and aldehyde dehydrogenase which breaks down the toxic byproducts of alcohol by which the metabolism of alcohol gets affected which results in the accumulation of the toxic by-product of alcohol known as acetaldehyde. The toxic acetaldehyde continues to build up in the body and causes painful symptoms while drinking alcohol.