|MadSci Network: Medicine|
This is not actually an allergic reaction, in so far as the immune system is not responding to the alcohol and none of the classic allergic symptoms are exhibited. Many people of Asain descent lack or have a disfunctional gene for Alcohol Dehydrogenase (ADH), an enzyme which the liver uses to metabolize alcohol and clear it from the system. The results of this deficit are that almost all of the alcohol consumed gets past the liver and into the blood stream, and that once in the system, it takes much longer for the alcohol to be removed. So people with an ADH deficiency become intoxicated faster after consuming less alcohol than normal, and remain intoxicated longer, exhibiting signs of systemic toxicity including the dilation of small blood vessels which result in migraine-like headaches and a reddened face.
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