The liver processes alcohol in two stages
After alcohol enters the bloodstream, the liver begins converting it into other chemicals. An enzyme called alcohol dehydrogenase turns ethanol—the alcohol in drinks—into acetaldehyde, a reactive compound that can damage cells. The liver then uses a different enzyme, aldehyde dehydrogenase, to convert acetaldehyde into acetate, a less harmful substance the body can further use and clear.
That second step matters because acetaldehyde is not simply alcohol in a new form. It can interfere with normal cell functions, and the body needs to keep converting it rather than letting it accumulate. Differences in how efficiently people process acetaldehyde can affect how they respond to alcohol.
When production outruns processing
During heavy drinking, the liver is receiving alcohol faster than it can handle it. Acetaldehyde continues to form, while the enzymes that process it work at a limited pace. If formation outstrips breakdown, acetaldehyde can build up temporarily. This helps explain why drinking a large amount quickly can be especially hard on the body: it creates a surge of alcohol to process, not just a longer period of exposure.
Acetaldehyde is one contributor to alcohol’s unpleasant effects, but it is not the whole explanation for a hangover. Alcohol also disrupts sleep and fluid balance, among other effects, and symptoms vary from person to person. The practical consequence is still clear: giving the liver more alcohol faster does not make it clear alcohol faster; it can leave more of the intermediate breakdown product waiting in the processing line.
