Drinking water alongside alcohol barely dents the hangover
Reviewing survey and experimental evidence, water taken during or after alcohol had only a modest effect on preventing a hangover, and none on one already under way.
What the study found
Water alongside alcohol barely dents the next day's hangover
The hangover and the thirst are two after-effects of drinking, not one causing the other. Reviewing the survey and experimental evidence, water taken during or after alcohol had only a modest effect on preventing a hangover and no relationship at all with severity once one had begun.
The caveat · Tested water, not the sachets
This concerns water, not electrolyte products, which were not tested here, so it undercuts the theory the hangover sachets rest on rather than testing the sachets themselves. It is a narrative review with no protocol or stated search, by a group that has argued this position for years. Much of the underlying evidence is people recalling their own drinking and their own hangovers. The authors do report that dehydration after alcohol is real, just mild and short-lived.