[1] Ebenezer Cobham Brewer writes in the Dictionary of Phrase and Fable (1898): "In Scotland it is a popular belief that a few hairs of the dog that bit you applied to the wound will prevent evil consequences.
Applied to drinks, it means, if overnight you have indulged too freely, take a glass of the same wine within 24 hours to soothe the nerves.
It is possible that the phrase was used to justify an existing practice, as the idea of "like cures like" (Latin: similia similibus curantur) dates back at least to the time of Hippocrates.
An early example of modern usage (poil de ce chien) can be found in Rabelais' 16th-century pentalogy Gargantua and Pantagruel,[3] literally translated by Motteux in the late 17th century.
In Finnish, consuming alcohol the next day is called tasoittava ("smoothener", "equalizer"), loiventava ("leveller") or korjaussarja ("a repair kit").
Also the phrase Sillä se lähtee millä tulikin that translates to "What caused it, will also cure it", describes the same concept.
[citation needed] In Puerto Rico, the relevant expression is matar al ratón, or "to kill the mouse".
The earliest known reference to the phrase "hair of the dog" in connection with drunkenness is found in a text from ancient Ugarit dating from the mid to late second millennium BC, in which the god ʾIlu becomes hungover after a drinking binge.
The text includes a recipe for a salve to be applied to the forehead, which consists of "hairs of a dog" and parts of an unknown plant mixed with olive oil.
In China, alcohol drunk to relieve a hangover is called huíhúnjiǔ (回魂酒), which literally translates as "the drink that brings back your soul".
[13] In Japan, the equivalent phrase is mukaezake (迎え酒), which can be literally translated as "alcohol for facing (greeting) the next day."