In fact, the blushing that occurs when drinking alcohol is due to the lack of acetaldehyde dehydrogenase in the body. After drinking alcohol, also known as ethanol, it is first turned into acetaldehyde by ethanol dehydrogenase, and then into acetic acid by acetaldehyde dehydrogenase, and finally excreted into the body. Both ethanol dehydrogenase and acetaldehyde dehydrogenase are enzymes secreted by the liver. The lack of acetaldehyde dehydrogenase causes the step of turning ethanol into acetaldehyde and then into acetic acid to change more slowly, which is the accumulation of acetaldehyde in the body, resulting in facial redness caused by capillary dilation. The eyes are rich in blood vessels, so they are particularly red after drinking because of the dilated blood vessels. This kind of people try to drink less, not recommended to drink a lot.