[header] How to deal with a hangover the day after [title] Re-hydrate your body. [step] Whether this can truly shorten or lessen a hangover or not, it is a fact that alcohol consumption does contribute to fluid loss and that re-hydrating is essential to getting your body back into balance. [substeps] Drink lots of water the day after a night of drinking. 
Try carrying a refillable bottle around with you. It's a good habit to get into even when you're not hungover.