Alcohol allergy is caused by the lack of the enzyme acetaldehyde of the body, an external symptoms of skin allergy reactions. Allergic to alcohol, two necessary conditions are allergy and alcohol, allergies are mostly the lack of acetaldehyde-converting enzyme in vivo. Alcohol, which is ethanol, in the body into acetaldehyde, because the lack of body-converting enzyme acetaldehyde, acetic acid can not be discharged into the body, so resulting the acetaldehyde poisoning, people will show a variety of allergy symptoms. The large amount of alcohol people, because this enzyme in the body more quickly out, and no symptoms of poisoning, and will not drink. Alcohol allergy, mostly allergies. Once the allergens allergies come into contact with alcohol, there will be a variety of allergy symptoms. These people are allergic, alcohol is the allergen, exposure to cause allergies to allergens.