Even if you've been to sleep after drinking, there could still be high levels of alcohol in your system, and this could be enough to put you well over the drink driving limit.
The safest and best advice is to avoid alcohol completely the night before you have to drive.
Whether it’s OK to drive the next morning depends on a lot of different factors, including how much you drank and if you've left enough time for your body to get rid of the alcohol. The amount of alcohol in your bloodstream depends on a few things, including the amount you take in, over what period of time and the speed at which your body gets rid of it.
On average, alcohol is removed from the body at the rate of about one unit an hour.1,2 But this varies from person to person. It depends on your size, whether you are male or female, how much food you’ve eaten, the state of your liver, and your metabolism (how quickly or slowly your body turns food into energy).3
There’s nothing you can do to speed up the rate alcohol leaves your system. 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.
The only way to eliminate alcohol from the body is to let time pass.
Remember, there’s no fail-safe way to guarantee all the alcohol you have drunk has left your system by the time you wake up the next day, so it’s important not to take risks.
In England, Wales and Northern Ireland, the alcohol limit for drivers is 80 milligrams of alcohol per 100 millilitres of blood, 35 micrograms per 100 millilitres of breath, or 107 milligrams per 100 millilitres of urine.4
The alcohol limit for drivers in Scotland is 50 milligrams of alcohol per 100 millilitres of blood, 22 micrograms of alcohol per 100 millilitres of breath, and 67 milligrams per 100 millilitres of urine.5
In most other European countries, the limit for drivers varies, but is, typically, 50 milligrams per 100 millilitres of blood.6 In some countries in Europe (including the Czech Republic, Hungary, Romania and Slovakia), the legal limit is zero, meaning it's illegal to drive with any alcohol in your system.
[1] Cederbaum, A.I. (2012). Alcohol metabolism. Clinics in Liver Disease, 16(4), 667-685.
[2] Jones, A.W. (2019). Alcohol, its absorption, distribution, metabolism, and excretion in the body and pharmacokinetic calculations. Wiley Interdisciplinary Reviews: Forensic Science, 1(5), e1340.
[3] Cederbaum, A.I. (2012). Alcohol metabolism. Clinics in Liver Disease, 16(4), 667-685.
