How Alcohol Leaves the Body — and Why Coffee Won't Sober You Up

Did last night's drinks clear by morning? Almost all alcohol is broken down by the liver at a roughly steady pace that coffee, a cold shower or a sauna cannot speed up. That pace differs several-fold between people, so neither the clock nor how you feel tells you your own level.

When to see a doctor

Right away — call 999 in the UK, 911 in the US, 112 in the EU: signs of alcohol poisoning — confusion, slurred speech or being unable to speak, vomiting, slow or irregular breathing, a seizure, pale or blue-tinged skin, being hard to wake or unconscious (NHS, UK; NIAAA, US). Also call if someone vomits blood and feels unwell, confused, faint or dizzy (NHS).

While you wait (NHS; St John Ambulance, UK):

Stay with them. They can choke on vomit or stop breathing, and the level can keep rising after the last drink, even in someone asleep.
If they do not respond, check whether they are breathing normally. Not breathing, or only occasional gasps: tell the call handler and start CPR as they instruct. Breathing normally: put them on their side in the recovery position.
If they are awake, sit them up. Give sips of water only if they are conscious, can swallow and are not vomiting.
Keep them warm with a coat or blanket.
Do not make them sick, give food, coffee or more alcohol, put them under a cold shower or in a bath, walk them around, or leave them to sleep it off alone.

The same day: you drank while taking a medicine that interacts with alcohol — sleeping pills, sedatives, opioids, some antihistamines, paracetamol, warfarin, diabetes medicines — and feel unusually drowsy, confused or unwell; call your pharmacist, doctor or NHS 111. Pregnant or breastfeeding and worried about what you drank — talk to your midwife or doctor.

Routinely: you often wake up needing a drink, or cannot remember the night before — see alcohol, honestly.

What is happening

The liver does the work. Enzymes in the liver turn alcohol into acetaldehyde, a toxic substance, and then into acetate. Less than a tenth leaves unchanged through breath, sweat and urine (Cederbaum, 2012; Jones, 2010), which is why a sauna, a run or sweating it out change very little.

The pace is roughly constant. After the first drinks the enzyme is working at capacity, so the level in the blood falls by about the same amount each hour however much was drunk (Jones, 2010). That rate is an average: in forensic studies it varies several-fold with genes, sex, drinking history and liver health, so no chart can give your own level.

Absorption continues after the last glass. Alcohol still in the stomach and gut keeps entering the blood, so the level can rise for a while after drinking stops — even in someone who has passed out (NIAAA).

Food changes the peak. Eating slows the stomach, so alcohol is absorbed more slowly and the peak is lower; some studies suggest food may also speed up clearance a little (Cederbaum, 2012). It still does not tell you when you are fit to drive.

Why people differ. At the same dose per kilogram, women tend to reach higher levels; older people clear alcohol more slowly and are more affected by interactions with medicines (NIAAA). Some people of East Asian descent carry an inactive form of the enzyme that clears acetaldehyde, which causes flushing and nausea (Cederbaum, 2012).

Coffee and cold water do not sober you up. They may make you feel more alert but do not lower blood alcohol, and in an overdose they can cause harm (NIAAA). The morning after is covered in what a hangover actually is.

Driving: the law, not a calculation

Legal limits are facts of law, not a guide to how much to drink:

England, Wales and Northern Ireland: 35 micrograms of alcohol per 100 ml of breath or 80 mg per 100 ml of blood; Scotland: 22 and 50 (GOV.UK).
US: 0.08% in every state except Utah, where it is 0.05%; 0.04% for commercial drivers; for drivers under 21, zero tolerance (NHTSA).

The UK government states that it is impossible to say how many drinks equal the limit, because it differs from person to person. The Highway Code warns that you may still be unfit to drive the morning after drinking, and advises not drinking at all if you are going to drive, since any amount affects driving. Even with a zero breath test, a hangover itself impairs attention and coordination behind the wheel (NIAAA; Alford et al., 2020).

What to do

Plan the way home before the first drink: a sober driver, a taxi or public transport.
Do not drive on how you feel or on the clock — the same applies the next morning.
Look after a very drunk friend: do not leave them alone, and call for help if any sign above appears. See also what to do if someone overdoses and watch your drink.
Skip detox products — detox cleanses don't work; before painkillers, read paracetamol vs ibuprofen.

When this is not the case

Pregnancy, breastfeeding, medicines that interact with alcohol and alcohol dependence change the whole question, not just the timing — see alcohol, honestly. With dependence, stopping suddenly can itself be dangerous (NHS).

Sources

Checked: 24 September 2026

How Alcohol Leaves the Body — and Why Coffee and a Cold Shower Don't Sober You Up