A typical hangover lasts between 8 and 24 hours, with most people feeling noticeably better by the end of that window. Symptoms tend to peak right around the time your blood alcohol level drops back to zero, which is why you often feel worst not while drinking but the morning after. In some cases, particularly after heavy or prolonged drinking, symptoms can stretch beyond 24 hours.
What a Normal Timeline Looks Like
Your body processes roughly one standard drink per hour. Once you stop drinking, your blood alcohol level steadily declines, and hangover symptoms ramp up as it approaches zero. For most people, that means waking up already at or near peak misery. From there, symptoms gradually ease over the course of the day.
A mild hangover from a few extra drinks might clear up in 8 to 12 hours. A more severe one, after a long night of heavy drinking, can take a full 24 hours or longer to fully resolve. The main variable is simple: how much you drank and over how long. The more alcohol your body has to process, the longer the recovery.
Why You Feel So Bad
A hangover isn’t just dehydration, though that plays a role. Several things happen simultaneously in your body, and each one contributes to different symptoms.
When your liver breaks down alcohol, it first converts it into a toxic compound that gets quickly converted again into acetate. Acetate levels stay elevated for at least six hours after drinking and trigger a chain reaction in your brain that increases levels of adenosine, a chemical linked to headaches and fatigue. This is likely why caffeine sometimes helps with hangover headaches: it blocks that exact chemical pathway.
Alcohol also suppresses a hormone that tells your kidneys to hold onto water. The result is frequent urination, which flushes out electrolytes your body needs to function normally. On top of that, alcohol disrupts sleep architecture. Even if you pass out quickly, your sleep quality tanks. You get less deep, restorative sleep and more fragmented, light rest in the second half of the night. That’s why you can sleep eight hours after drinking and still feel exhausted.
Factors That Make It Last Longer
Not all hangovers are created equal, even at similar drinking levels. Several factors can push your recovery well past the 24-hour mark.
What you drank matters. Darker liquors like bourbon, red wine, and brandy contain higher levels of congeners, the chemical byproducts of fermentation that give drinks their color and flavor. Research published in Alcohol and Alcoholism found that high-congener drinks produce more severe hangovers, and it takes fewer of them to trigger one. Clear spirits like vodka and gin have far fewer congeners.
Your age changes the equation. As you get older, your total body water decreases and your liver clears alcohol more slowly. According to Harvard Health, this means older adults reach higher blood alcohol concentrations than younger people after drinking the same amount. The practical result: hangovers hit harder and take longer to shake off as you age.
Genetics play a significant role. About 30% of people with East Asian ancestry carry a gene variant that dramatically reduces their ability to break down acetaldehyde, the toxic intermediate step in alcohol metabolism. Carriers of this variant experience more intense flushing, nausea, and discomfort from smaller amounts of alcohol. But genetic variation in alcohol-processing enzymes exists across all populations and can influence how quickly your body clears alcohol’s byproducts, even if you’ve never experienced facial flushing.
Empty stomach, poor sleep, and overall health all compound the problem. If you were already dehydrated, sleep-deprived, or hadn’t eaten much before drinking, your body starts recovery from a deficit.
What Actually Helps (and What Doesn’t)
Time is the only real cure. Your body needs hours to clear toxic byproducts, restore electrolyte balance, and rehydrate tissues. No supplement, pill, or “detox” drink has been shown to meaningfully shorten that process.
What you can do is support your body while it recovers. Drinking water or electrolyte beverages helps replace what you lost. Eating bland, easy-to-digest food gives your body fuel and can settle nausea. Rest, even if you can’t sleep deeply, lets your system focus on recovery. Caffeine may help with the headache specifically, since it blocks the adenosine buildup that contributes to hangover head pain, but it can also worsen dehydration if you’re not drinking water alongside it.
The “hair of the dog” approach, drinking more alcohol to ease symptoms, doesn’t speed recovery. It just delays it by adding more alcohol for your body to process.
When It’s More Than a Hangover
A hangover that fades over 24 hours, however unpleasant, is normal and resolves on its own. But some symptoms after heavy drinking signal something more serious.
Alcohol poisoning can look like a bad hangover in its early stages, but it’s a medical emergency. The key differences: confusion or inability to stay conscious, vomiting while passed out, seizures, slow or irregular breathing, and dangerously low body temperature. These symptoms typically appear while someone is still drinking or shortly after, not the next morning. If someone shows these signs, they need emergency help immediately.
If you regularly experience hangovers that last two or more days, or if you notice symptoms like tremors, severe anxiety, or hallucinations after stopping drinking, those may be signs of alcohol withdrawal rather than a standard hangover. Withdrawal happens when your body has adapted to frequent alcohol use and reacts to its absence.