Do electrolytes help a hangover?
They can help with one piece of it. Alcohol makes you urinate more while you drink, and vomiting or sweating on a night out adds to the loss, so you may wake up short on fluid. An electrolyte drink replaces water along with sodium and potassium, which helps the body hold on to that water.
What electrolytes do not do is fix the rest of a hangover. In human studies, electrolyte concentrations and dehydration markers measured the morning after were not significantly correlated with hangover severity. NIAAA's hangover guidance makes the same point: research has not found a clear relationship between electrolyte disruption and hangover severity, or proof that added electrolytes reduce it.
Sources: Penning et al., 2010: The pathology of alcohol hangover; Hangovers: causes, remedies, and safety
