Auto-Brewery Syndrome (ABS), or Gut Fermentation Syndrome, is an uncommon condition where a person becomes intoxicated without drinking alcohol. This happens when certain microbes in the digestive system, especially yeasts like Saccharomyces cerevisiae, ferment sugars from food and turn them into ethanol right inside the gut.
Everyone has a mix of microbes in their intestines, and some naturally produce trace amounts of alcohol. Normally, the liver clears it before it causes any issues. But in ABS, ethanol is produced faster than the body can break it down, leading to a rise in blood alcohol levels and symptoms of drunkenness.