No Cure But Time

In theory the spell greater restoration would work, as hangovers are likely a level of exhaustion or two. As has been noted, dehydration is a large part of becoming hungover, so dying of thirst is akin to a lethal hangover. But, if there are any other side effects or aspects to being “hungover” then the spell would not technically remove those penalties. You need to break out a wish spell to be sure.

Hangovers. Even in a magical world of dragons and wizards there’s no real cure.