When patients claim they haven’t touched a drop despite signs of inebriation they could be telling the truth, based on the case of a US ‘drunk driver’ whose stomach was effectively brewing beer.

The 46-year-old abstainer, who was arrested for presumed drink-driving and hospitalised after refusing a breathalyser analysis, was eventually found to be suffering from auto-brewery syndrome (ABS), according to doctors from the Richmond University Medical Center in New York.

His initial blood alcohol reading after his arrest was 0.2%, and police and hospital staff refused to believe him when he insisted that he hadn’t been drinking.

The otherwise healthy man had been experiencing memory loss, episodes of depression and mental changes for six years, following a prolonged course of antibiotics for a complicated thumb injury, the doctors wrote in BMJ Open Gastroenterology.