It doesn’t happen to everyone, but for some people, going out and having drinks results in a deeply flushed face. Why? Because their bodies are not fully able to process the alcohol they consume, so an alcohol-related chemical called acetaldehyde builds up in their bodies. It’s the acetaldehyde that triggers the flushed face.
http://www.narconon.org/blog/red-face-after-drinking-a-dead-giveaway-of-alcohols-damaging-effects.html
Toms Blog on Life and Livingness