What Is a Hangover?Posted: 2012/01/03
When we metabolize alcohol, our livers create an extremely toxic substance called acetaldehyde. Humans have handy enzymes that break down acetaldehyde called acetaldehyde dehydrogenase and glutathione. But when we drink too much, the enzymes can’t keep up, and the toxin builds up, increasing the severity of headaches and nausea. To give you an idea of how toxic acetaldehyde is: Antabuse, a drug used in severe cases of alcoholism, completely blocks the acetaldehyde-eating enzymes. The result is that even a drop of alcohol causes a flushed face, headache, nausea, vomiting, chest pain, weakness, blurred vision, mental confusion, sweating, choking, breathing difficulty, and anxiety.
via What Is a Hangover?.