Red spots on the arms after drinking alcohol may be due to an allergic skin reaction caused by alcohol allergy, and hives, eczema and other symptoms will also appear. After drinking alcohol, ethanol should be completely oxidized to water and carbon dioxide under the action of the enzyme acetaldehyde dehydrogenase, but people with alcohol allergy usually lack the enzyme acetaldehyde dehydrogenase, which leads to the accumulation of ethanol in the body. The ethanol gathered in the body will lead to localized congestion and redness caused by the dilation of small blood vessels in the skin, usually without itching. In addition, it can occur on the face and chest in addition to the arms. People who are allergic to alcohol can be treated with anti-allergy therapy, such as oral antihistamines such as paracetamol. The key treatment is to stop drinking alcohol immediately and drink plenty of water, and the erythema may gradually subside. Erythema on the arm should be promptly consulted in a regular hospital if it fails to improve. The presence of alcohol allergy suggests that it is best not to drink alcohol again.