What Is The Origin Of The Phrase "Hair Of The Dog"?
The expression the hair of the dog, for an alcoholic drink taken to cure a hangover, is a shortening of ‘a hair of the dog that bit you’. It comes from an old belief that someone bitten by a rabid dog could be cured of rabies by taking a potion containing some of the dog's hair. The correlation suggests that, although alcohol may be to blame for the hangover (as the dog is for the attack), a smaller portion of the same will, paradoxically, act as a cure. There is, it should be added, no scientific evidence that the cure for either a hangover or rabies actually works.
From Oxford Dictionary of Word Origins ©2010.
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