The short answer: most hangovers last up to 24 hours. They typically peak a few hours after your blood alcohol returns to zero — often the next morning — and ease through the day.
The typical timeline
Symptoms usually begin as your blood alcohol drops toward zero, peak the following morning, and fade over the next several hours. A heavy night can occasionally leave you feeling off into a second day.
What makes it last longer
More total alcohol, high-congener drinks, poor sleep, dehydration, and genetics all stretch it out. If you flush when you drink, an ALDH2 gene variant can slow acetaldehyde clearance and prolong things.
How to shorten it
Hydrate with electrolytes, eat something gentle, rest, and give it time. What actually helps once you're hurting. Better yet, prevent the next one: the prevention guide and a Gush before you drink.
Always drink responsibly. This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.