A typical hangover lasts up to 24 hours. Symptoms usually begin 6 to 8 hours after drinking, once your blood alcohol level drops significantly, and they peak right around the time your body finishes processing all the alcohol. Most people feel noticeably better by the following evening, though heavier drinking sessions can push symptoms past the 24-hour mark.
When Symptoms Start and Peak
Hangovers don’t hit while you’re still drunk. They begin as your blood alcohol concentration falls, typically 6 to 8 hours after your last drink. If you stop drinking at midnight, you can expect symptoms to set in around 6 to 8 a.m. The worst of it arrives when your blood alcohol reaches zero, which for most people lines up with late morning or early afternoon the next day.
This timing explains why you might wake up feeling rough but then feel even worse a few hours later. Your body is still clearing alcohol from your system when you first open your eyes, and the hangover intensifies as that process finishes. From that peak, symptoms gradually taper off over the next several hours. If you’re still feeling sick after a full 24 hours, that’s a signal something else may be going on.
What’s Actually Happening in Your Body
Your liver breaks alcohol down in stages. The first step converts it into a toxic compound called acetaldehyde, which then gets converted again into harmless acetic acid. That middle step is the problem. Acetaldehyde is significantly more toxic than alcohol itself, and while it’s circulating, it contributes directly to nausea, headache, and the general misery of a hangover.
How quickly you clear acetaldehyde depends on your genetics. Some people, particularly those of East Asian descent, produce a slower version of the enzyme responsible for breaking it down. This leads to more intense symptoms like facial flushing and a longer recovery window from the same amount of alcohol.
On top of the acetaldehyde problem, your immune system gets involved. Research measuring immune markers during hangovers found that several inflammatory signals are elevated even after blood alcohol drops to zero. These are the same types of molecules your body produces when fighting an infection, which is part of why a hangover can feel so similar to being sick. That inflammatory response takes time to resolve on its own, independent of how fast your liver works.
Why Some Hangovers Last Longer Than Others
The single biggest factor is how much you drank. More alcohol means more acetaldehyde to process, more dehydration, more disrupted sleep, and a longer overall recovery. But several other variables shift the timeline in meaningful ways.
What you drank matters. Darker spirits like bourbon and whiskey contain higher levels of congeners, byproducts of fermentation that your body has to process alongside the alcohol itself. Studies have found that hangover severity scores are significantly higher after bourbon compared to the same amount of vodka, even when both produce the same peak blood alcohol level. If you’re choosing between drinks and want to minimize tomorrow’s damage, lighter-colored, more heavily filtered options tend to produce milder hangovers.
Sleep disruption plays a role. Alcohol fragments your sleep architecture, reducing the amount of deep, restorative sleep you get even if you’re unconscious for eight hours. Poor sleep quality amplifies fatigue, brain fog, and irritability the next day, extending the period where you feel “off” even after the core hangover symptoms fade.
Your body size, biological sex, and age all contribute. Smaller people reach higher blood alcohol levels from the same number of drinks. Women generally have less of the enzyme that breaks down alcohol in the stomach, leading to higher absorption. And as you age, your liver processes alcohol more slowly, which is why the same amount of drinking that barely registered at 25 can wreck an entire day at 40.
Does Drinking Water Actually Help?
This is one of the most persistent pieces of hangover advice, and the research is surprisingly clear: water doesn’t do much. A study from Utrecht University found that drinking water during or after alcohol consumption had only a modest effect on preventing next-day hangovers. Even more notably, the amount of water consumed during the hangover itself was unrelated to changes in hangover severity.
The researchers concluded that dehydration and hangovers are two separate consequences of drinking that happen to occur at the same time. Dehydration effects tend to be mild and short-lived, while hangover symptoms are more enduring and driven by different mechanisms, primarily the toxic byproducts of alcohol metabolism and the immune system’s inflammatory response. Drinking water will help with thirst and dry mouth, but it won’t meaningfully shorten how long you feel hungover.
What Can Shorten Recovery
Since no single remedy addresses all the mechanisms driving a hangover, recovery is mostly about giving your body time and minimizing additional stress on it. Eating before and during drinking slows alcohol absorption, which reduces the peak concentration your liver has to handle. A meal with fat and protein is more effective at this than simple carbohydrates.
Anti-inflammatory pain relievers can take the edge off headaches and body aches, though anything processed by the liver adds to its workload. Sleep is genuinely restorative here. If you can sleep through the worst of the peak, you’ll feel better when you wake up simply because time has passed and your body has done more of its cleanup work. Light, easy-to-digest food when you’re able to eat again helps stabilize blood sugar, which drops during heavy drinking and contributes to shakiness and fatigue.
The most reliable way to shorten a hangover is to reduce how much you drink in the first place. Keeping your peak blood alcohol lower means less acetaldehyde, less inflammation, and a faster return to normal. For most people, that translates to a hangover that resolves well within 12 hours rather than dragging through a full day.