How long does alcohol stay in your system and when it is safe to drive?

WHEN you’re enjoying a few pints at the pub with your friends, it’s easy to forget the impact alcohol can have on your body.

But alcohol is a powerful chemical that can take longer to leave your body than you might think.

Alcohol may take longer to leave your system than you might think


Alcohol may take longer to leave your system than you might thinkPhoto credit: Getty

Although it varies from person to person, it can drastically change your judgment and behavior.

You may feel fairly sober, but your reaction times become slower and you typically become more reckless and uninhibited.

This can have disastrous consequences if, for example, you drive a car while under the influence of alcohol.

And when you drink water or have a cup of coffee, you may not clear your head the way you want.

How long does alcohol stay in your system?

According to the NHS, it normally takes the liver around an hour to remove one unit of alcohol from the body.

So a pint of weak to medium beer will stay in your system for between 90 minutes and two hours.

According to American Addiction Centers, in most cases alcohol is detectable between six and 72 hours.

However, this depends on the test used and how often the person drinks.

For example, blood tests will show alcohol for up to 12 hours, while breath can take up to 24 hours.

Urine typically detects alcohol 12 to 24 hours after a session and remains in saliva for about 12 hours.

But any amount of drinking and driving can be fatal, no matter how much alcohol you’ve consumed.

Sometimes it can feel like a hangover lasts two days, and other times you wake up feeling like you haven’t had anything to drink.

However, neither is a true indication of how much alcohol is actually in your system.

The government sets strict drink-driving limits to prevent drink-driving deaths, of which there are an estimated 7,800 in the UK each year.

Dr. Fiona Sim OBE, Drinkaware’s chief medical adviser, said the amount of alcohol in your bloodstream depends on three things.

First, the amount you consume. Secondly, the time period. And finally, the speed at which your body gets rid of it.

Alcohol leaves your body at a rate of about one unit per hour – but this can vary from person to person.

Your height, your gender, the condition of your liver, your metabolism, whether you’re stressed, and how much you’ve eaten can all affect how quickly or slowly your body can process alcohol.

And there’s no test you can take at home or in the pub to get these answers – so experts say it’s best to avoid the risk of drink driving entirely.

Can I sleep off alcohol?

It is often mistakenly assumed that the effects of alcohol wear off while you sleep, even if you have a foggy head in the morning.

However, sleep does not affect the rate at which alcohol leaves your bloodstream.

Research by the Institute of Advance Motoring suggests that people do not understand that the mere fact that they have slept does not mean that they are no longer affected by alcohol.

It says: “Many drivers who wouldn’t think about driving after a night in the pub don’t recognize the impact of alcohol on their body the next day or simply ignore its effects.”

Can I drink coffee or water to speed it up?

Drinkaware warns that there is nothing you can do to speed up your alcohol output.

The leading charity said: “A cup of coffee or a cold shower won’t help you get rid of alcohol.”

“You may feel a little different, but you won’t have eliminated the alcohol in any way.”

“The only way to eliminate alcohol from the body is to allow time to pass.”

But drinking coffee can help you wake up, and water can help rehydrate you – both of which are useful for a hangover.

However, keep in mind that none of these measures change the basic amount of alcohol in your body.

This also applies to the evening before.

Drinking a pint of water before bed may relieve your headache the next morning, but it won’t change the level of alcohol in your system.

How many units are in an alcoholic drink?

The number of units in an alcoholic beverage can vary depending on the strength of each brand.

But roughly speaking, these are the units in popular drinks:

  • 175 ml glass of average strength wine (12%) = 2.1 units
  • 250 ml glass of medium strength wine (12%) = 3 units
  • Single measure of spirits = 1 unit
  • Pint of hard lager, beer or cider (5.2%) = 3 units
  • Pint of light lager, beer or cider (3.6%) = 2 units

What is the drink driving limit in the UK?

Government guidelines say the limit in England, Wales and Northern Ireland is 80 milligrams of alcohol per 100 milliliters of blood, 35 micrograms per 100 milliliters of breath or 107 milligrams per 100 milliliters of urine.

In Scotland the limits are 50 milligrams of alcohol per 100 milliliters of blood, 22 micrograms per 100 milliliters of breath or 67 milligrams per 100 milliliters of urine.

There is no way to know how many milligrams a unit of alcohol produces in your bloodstream.

How much can I legally drink?

The government says it is “impossible” to say how many drinks are safe to avoid exceeding the limit because every person is different.

However, the evidence is clear: drinking alcohol impairs your ability to drive.

As a rule of thumb, two pints of regular strength lager or two small glasses of wine would put you over the limit.

However, this is not a general rule.

As explained previously, factors such as weight, gender, metabolism, and the amount you’ve eaten all influence the way your body processes alcohol, so everyone has different limits.

There is no foolproof way to drink alcohol and stay within the limit.

Many people have a one drink limit, but there is no way to prove whether that is too much or too little.

What if I have to drive the morning after drinking?

Drinkaware’s advice is that even small amounts of alcohol can affect your ability to drive and there is no foolproof way to drink alcohol and stay within the limit.

Guidance it says: “The police advice is clear: avoid alcohol completely if you plan to drive.”

“Because there is no way to speed up the time it takes for your body to process alcohol in your system, there is no fail-safe way to guarantee that all the alcohol you drank will be gone when you wake up the next day.”

There are Tools available to calculate the units in your favorite drink on

There is also an app you can download to keep track of your sessions over an evening.

If you really want to make sure you can drive safely, you can use a home breathalyzer like the one available from Alcosense before you hit the road.

Russell Falcon

Russell Falcon is a USTimesPost U.S. News Reporter based in London. His focus is on U.S. politics and the environment. He has covered climate change extensively, as well as healthcare and crime. Russell Falcon joined USTimesPost in 2023 from the Daily Express and previously worked for Chemist and Druggist and the Jewish Chronicle. He is a graduate of Cambridge University. Languages: English. You can get in touch with me by emailing

Related Articles

Back to top button