Alcohol hangover versus dehydration revisited

An alcohol hangover is a combination of negative mental and physical symptoms that can be experienced after a single episode of alcohol consumption, starting when blood alcohol concentration (BAC) approaches zero. A popular theory suggests that dehydration is the primary cause of alcohol hangover and that the consumption of water could alleviate hangover symptoms. In a paper published in the journal Alcohol, the current evidence on the relationship between hangover severity, thirst, and water consumption is summarised.
The positive correlations of the amount of water consumed with both hangover severity and thirst suggest that both dehydration and the hangover are co-occurring after-effects of alcohol consumption. While hangovers were typically relatively enduring, dehydration effects were usually mild and short-lasting. Survey data revealed that water consumption during or directly after alcohol consumption had only modestly prevented next day hangovers. Also, the amount of water consumed during a hangover was not related to changes in hangover severity and thirst. Thus, water consumption was not effective in alleviating the alcohol hangover.
Taken together, these data suggest that alcohol hangover and dehydration are two co-occurring but independent consequences of alcohol consumption.
Source: Mackus M, Stock AK, Garssen J, Scholey A, Verster JC. Alcohol hangover versus dehydration revisited: The effect of drinking water to prevent or alleviate the alcohol hangover. Alcohol. 2024 Jul 26:S0741-8329(24)00100-9.