Hangover cures

A hangover is not one mechanism, which is exactly why no single product fixes it. At least five things are happening at once:

• Fluid loss. Alcohol suppresses the hormone that limits urine output, so fluid and electrolytes go out faster than they come in. Real, and smaller than its reputation: when researchers compared markers of dehydration against how bad people rated their hangovers, the two were not significantly related.⁷ Water is worth drinking for thirst and dry mouth. It is not the lever people think it is.
• Acetaldehyde. Your liver converts alcohol to acetaldehyde, a considerably more toxic compound, before breaking it down further. People who clear it slowly feel markedly worse.
• An inflammatory response. Drinking raises inflammatory signalling molecules, and of everything that has been measured against reported hangover severity, immune factors show the strongest relationship.⁷ This is the part nothing on the shelf reliably touches, and the best current answer to why a hangover feels like being ill.
• Wrecked sleep. Alcohol shortens the time to fall asleep and then fragments the night and suppresses its deep stages, so you wake under-slept regardless of hours in bed.
• Congeners. The flavour compounds in darker drinks make hangovers measurably worse at the same dose. In the trial that tested it, bourbon produced a worse hangover than vodka while next-day cognitive impairment was identical,⁴ which is a useful reminder that feeling better and being less impaired are different things.

Both common options have a real trade-off the morning after a heavy night, and the internet's confident version of this advice is usually wrong in one direction or the other.

Paracetamol, or acetaminophen, is processed by a liver pathway that heavy regular drinking makes more active, which is why the risk of liver injury concentrates in regular heavy drinkers and at doses above the label rather than in someone who had a big night once.⁵ It is not a reason for panic; it is a reason to stay within label doses and to take the warning seriously if drinking is frequent.

Ibuprofen and aspirin irritate a stomach lining that alcohol has already irritated, which matters most if you are nauseated, have been vomiting, or take them regularly.

None of this is medical advice, and none of it is a reason to double a dose. If you are on other medication or have any liver or stomach condition, the pharmacist who answers this question for free knows more about your case than any website.

The only reliable lever is the dose. Hangover severity tracks how much alcohol you drank far more closely than what you drank, in what order, or what you took alongside it.¹ Beyond that, four things have honest support:

• Eat before and while. Food slows absorption and lowers the peak. Afterwards it only feeds you.
• Alternate with water. It paces the drinking as much as it hydrates, and both help.
• Lighter-coloured drinks, at the same dose. Fewer congeners, milder hangover, no change to how impaired you are.⁴
• Protect the sleep. Stopping earlier does more for the morning than anything you can take at 2am, because it gives the alcohol time to clear before you sleep.
• Pre-drinking probiotics: plausible mechanism, unproven effect. Taken before the first drink, these target acetaldehyde in the gut rather than the alcohol itself, which is real chemistry rather than marketing. The limitation is where they work: your liver does the overwhelming majority of alcohol metabolism, and a probiotic only reaches what is in your intestine. A few strains have measurably lowered acetaldehyde in people, but check who ran those studies before spending on them: a few dozen participants each, and authors who work for the company selling the product. None tested a heavy night, and none claimed to prevent a hangover. The best-known brand has no published human trial showing it reduces hangovers. Worth saying plainly: the open question here is whether they work, not whether they are safe. The engineered strain sold for this has been evaluated by independent toxicologists, and unproven is not the same accusation as dangerous.

The fair test for anything sold to prevent a hangover is not whether it cures one, which nobody claims, but whether it beats the four habits above it. Nothing on the market has shown that it does, and drinking less remains the only intervention with a large and consistent effect.

For the morning itself, the boring version works: fluids with electrolytes, something to eat, and more sleep. Our sister site has a free homemade electrolyte drink calculator for exactly this, and SleepTools covers the sleep half of the repair.

The two clocks are different, and confusing them is how people end up driving over the limit at breakfast. A hangover can start while your blood alcohol is still well above zero, and it routinely outlasts it by hours. Feeling terrible tells you nothing about your BAC in either direction.

If last night was heavy, the sober-up estimator gives a window for when the alcohol itself likely clears, and how to sober up covers why none of the remedies above move that number by a minute.

Confusion, vomiting while drowsy, slow or irregular breathing, cold, clammy or blue-tinged skin, seizures, or someone who cannot be woken are signs of alcohol overdose, not a rough morning, and blood alcohol can keep rising after someone passes out.⁶ That is an emergency call: 911 in the US, 112 in Europe. Persistent vomiting, severe abdominal pain, or symptoms lasting beyond a day are worth a doctor rather than a remedy.