A patient appears intoxicated and has elevated blood alcohol levels, yet insists they have not consumed alcohol. At IBS Days in Bologna, William Fusco, a gastroenterologist at Rome’s Policlinico Gemelli, discussed one rare possible explanation: auto-brewery syndrome, also known as gut fermentation syndrome.

The condition arises when ethanol-producing bacteria or fungi in the gut generate excessive amounts of alcohol from dietary carbohydrates. Small amounts of ethanol are normally produced in the body, but in affected patients a carbohydrate-rich meal can trigger a marked rise in blood alcohol levels. The resulting symptoms may resemble those of alcohol intoxication, making the syndrome particularly difficult to recognize.

Fusco explains how measuring blood ethanol before and after a controlled carbohydrate challenge can help investigate a suspected case. Identifying whether bacteria or fungi are responsible is then crucial to choosing an appropriate antimicrobial treatment. For severe cases, he also discusses fecal microbiota transplantation as a potential option.