Excerpted from You’re Doing It Wrong

The phrase comes from an old folk remedy for rabies: treat a bite from a rabid dog by applying hair from the same dog to the wound. The medical logic was nonexistent, but the phrase migrated into drinking culture as a description of consuming more alcohol to treat the aftereffects of alcohol.

There is a narrow physiological mechanism that makes this partially coherent in the worst possible way.

Some of a hangover’s symptoms — particularly those associated with drinking large amounts of cheap or dark liquors — are partly caused by methanol, a trace byproduct of fermentation that metabolizes into formaldehyde and formate, both toxic. The body processes methanol using the same enzyme (alcohol dehydrogenase) that processes ethanol. If you flood the system with more ethanol, the enzyme preferentially metabolizes the ethanol, buying time for the methanol to be excreted through the lungs and kidneys before it converts into formaldehyde. This is actually the basis for using ethanol (or fomepizole) in emergency treatment for methanol poisoning.

So in a narrow technical sense, additional alcohol may slightly delay the processing of certain toxins.

The problem: it doesn’t cure the hangover. It postpones it. The dehydration, electrolyte depletion, disrupted sleep architecture, gastrointestinal inflammation, and acetaldehyde accumulation that cause most hangover symptoms are not addressed by more alcohol. They are compounded. The “cure” simply delays the reckoning while potentially increasing overall alcohol consumption.

The actual evidence-based approaches to hangover reduction are unglamorous: water and electrolytes before sleep, food to slow alcohol absorption during drinking, time for the liver to clear acetaldehyde. The hair of the dog is a way to not be sober yet. That’s all it is.

As an always recovering alcoholic, my best advice is to not to drink in the first place. More and more we learn of its negative effects, even in moderation.