Red face when drinking, why?

A drink on the blush, may be born lack of aldehyde dehydrogenase, aldehyde dehydrogenase deficiency will lead to alcohol in the body can not be metabolized, acetaldehyde accumulation in the body, acetaldehyde will make blood vessels dilated, so there will be blush phenomenon. Acetaldehyde dehydrogenase deficiency, it is best not to drink or drink less.