A Texas man who stumbled into an emergency room complaining of dizziness was found to have a blood alcohol level five times the driving limit.
The strange thing was, he hadn't drunk any alcohol that day. And it wasn't the first time he'd shown signs of intoxication while otherwise stone-cold sober.
"He would get drunk out of the blue - on a Sunday morning after being at church, or really, just anytime," nurse Barabara Cordell told news outlet NPR.
"His wife was so dismayed about it that she even bought a Breathalyser."
The 61-year-old did like to brew his own beer, which gave doctors an idea. They isolated him in a room at the hospital for a day, and fed him carbohydrate-rich food.
Their suspicions were proven correct when his blood-alcohol level spiked to 0.12 percent – he had an infection of yeast microbe Saccharomyces cerevisiae, and his gut was acting like a miniature biological brewery.
The condition, labelled "auto-brewery syndrome" in the International Journal of Clinical Medicine, is extremely rare and has never been studied properly.
"This is a rare syndrome but should be recognised because of the social implications such as loss of job, relationship difficulties, stigma, and even possible arrest and incarceration," the journal claimed. "It would behove health care providers to listen more carefully to the intoxicated patient who denies ingesting alcohol."
The man was reportedly cured by switching to a low-carb diet and taking anti-fungal medication.