Asked by: Caroline Paget, Edinburgh
There is no simple answer. The rate at which your body breaks down alcohol depends on many factors, including your age, sex, weight, metabolism and how much you’ve eaten. As a general rule of thumb, it takes about one hour for your body to break down one ‘unit’ (10ml of pure alcohol). A pint of low strength lager contains about two units, while a higher strength one has three. So it could take 18 hours or longer for the alcohol from six pints of strong lager to leave your system. In other words, at least some alcohol will still be in your blood the morning after the night before.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.