How long does it take for alcohol to leave your system? Units explained

WHEN you're enjoying a couple of pints in the pub with your mates, it's easy to forget about the impact alcohol can have on your body.

But booze is a powerful chemical which can take longer to leave your system than you might think.

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While it varies from person to person, it can drastically alter your judgement and behaviour.

You might feel pretty sober, but your reaction times will be slower and you usually become more reckless and uninhibited.

This can have disastrous consequences, like if you get behind the wheel of a car while under the influence, for example.

And chugging water or downing a mug of coffee might not clear your head in the way you think it will.

How long does alcohol stay in your system?

It usually takes the liver about an hour to remove one unit of alcohol from the body, according to the NHS.

So one pint of weak-to-medium-strength beer will remain in your system for between 90 minutes and two hours.

Booze tends to be detectable between six and 72 hours in most cases, American Addiction Centers says.

But this will vary depending on the test used, and how often the person drinks.

In blood tests, for example, alcohol will show for up to 12 hours, while this could be as many as 24 hours on the breath.

Urine tends to detect booze for between 12 to 24 hours after a session, and it sticks around in saliva for about 12 hours.

But any amount of drink-driving can kill - no matter how many drinks you've had.

Sometimes it can feel like a hangover lasts two days, and other times you wake up feeling like you didn't drink.

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

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

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

Firstly the amount you consume. Secondly, the period of time. 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 size, gender, state of your liver, metabolism, whether you are stressed and how much you've eaten can all affect how quickly or slowly your body can process alcohol.

And there is no at-home, or at-pub, test you can take to give you those answers - hence why experts say it's best to avoid the risk of drink driving entirely.

Can I sleep alcohol off?

People often wrongly assume that the effects of alcohol wear off as you sleep, even if you have a fuzzy head in the morning.

But sleep has no bearing on the rate at which alcohol leaves your bloodstream.

Research by the  suggests that people don't understand that just because they've been to sleep, it doesn't mean they are no longer affected by alcohol.

It states: "Many drivers who would not consider driving after a night in the pub fail to recognise the influence of alcohol on their body the next day, or simply choose to ignore its effects."

Can I drink coffee or water to speed it up?

There's nothing you can do to speed up the rate that alcohol leaves your system, Drinkaware warns.

The leading charity said: "Having a cup of coffee or a cold shower won’t do anything to get rid of the alcohol.

"You might feel slightly different, but you won’t have eliminated the alcohol in any way.

But drinking coffee might help wake you up, and water will help to rehydrate you - both of which are useful for a hangover.

However, remember that neither of these changes the fundamental amount of alcohol in your body.

This goes for the night before, too.

Drinking a pint of water before bed might alleviate your headache the next morning, but it won't change the level of alcohol in your system.

What is the drink-driving limit in the UK?

Government guidelines state that the limit in England, Wales and Northern Ireland is 80 milligrammes of alcohol per 100 millilitres of blood, 35 microgrammes per 100 millilitres of breath or 107 milligrammes per 100 millilitres of urine.

In Scotland, the limits are 50 milligrammes of alcohol per 100 millilitres of blood, 22 microgrammes per 100 millilitres of breath or 67 milligrammes per 100 millilitres of urine.

There is no way of knowing how many milligrammes one unit of alcohol will produce in your bloodstream.

How much can I legally drink?

The Government says it is "impossible" to say how many drinks are safe to avoid going over the limit, based on the fact everyone is different.

But the evidence is clear - that drinking 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.

But this isn’t a catch-all rule.

As explained, factors like weight, sex, metabolism and how much you’ve eaten all contribute to how your body processes alcohol, so everyone has different limits.

There is no fool-proof way of drinking and staying under the limit.

Many people have a one-drink limit but there is no way of proving whether this is too much or too little.

What if I need to drive the morning after drinking?

Advice on Drinkaware states that even small amounts of alcohol can affect your ability to drive, and there is no fool-proof way to drink and stay within the limit.

states: "The advice from the police is clear: avoid alcohol altogether if you plan to drive.

"Because there is no way to speed up how long your body takes to process any alcohol in your system, there’s no fail-safe way to guarantee all the alcohol you have drunk will be gone by the time you wake up the next day."

There are to calculate the units in your favourite tipple at Drinkaware.com.

It also has an app you can download to keep track of your units on a night out.

If you really want to make sure you are safe to drive, you could use a home breathalyser like the ones sold by before you take to the roads.