Where does the expression ‘hair of the dog’ come from?
The expression ‘hair of the dog’ refers to the idea that drinking more alcohol can cure a hangover. The full expression is: ‘to take a hair of the dog that bit you.’
The idea is an old one; that the cause of a problem can also be the antidote. However taking a hair of the dog is not recommended by medical experts because it is merely extending the period before the hangover. Try drinking some water and going back to bed!