The Idiom Attic - a collection of hundreds of English idioms, each one explained.
The meaning of "hair of the dog"
" Hair of the dog "
An alcoholic drink, intended to cure a hangover. It is mistakenly believed that a small measure of the same drink that made a person drunk will sober them up and cure the drinks ill effects. The expression is also used in other contexts, whenever an additional dose of whatever caused a problem is thought to be an appropriate remedy.
I feel rough. I shouldn't have had those last six tequila slammers last night. Here goes another - maybe it will be the hair of the dog.