How long does alcohol stay in the blood?

On average it takes about one hour for your body to process one unit of alcohol. This varies depending on your body size, sex and the amount of food in your digestive system. If your liver isn't functioning normally, the process takes longer. One unit of alcohol is roughly equivalent to half a pint of beer, a 25ml shot of spirits, or two-thirds of a small (125ml) glass of wine. This means that one pint takes your body about two hours to break down, and a large glass of wine (250ml) about three hours - longer if the ABV (alcohol by volume) content is higher than average. So if you have seven pints during a night out, it could take as long as 17 or 18 hours to leave your system.

It's very important to think about how long it takes your body to process alcohol before doing activities such as driving or operating machinery. Even if you feel fine the day after drinking, you could still be over the limit.

To avoid putting your health at risk, women shouldn't drink more than 14 units a week, and men shouldn't drink more than 21. Nor should you 'use up' all your units in one go - women shouldn't drink more than 2-3 units a day, and men should limit themselves to 3-4.