A woman kept getting drunk despite not drinking. Fungi in her gut were brewing their own alcohol.

A woman kept ending up in the emergency room with excessive sleepiness, slurred speech and the scent of alcohol on her breath, but she had not ingested a drop of liquor. It turns out that microbes in her gut were brewing their own booze — and making her drunk.

Doctors eventually diagnosed her with a rare condition called auto-brewery syndrome. But before that, the 50-year-old had been referred to emergency departments seven times over the course of two years. Each time, her symptoms were similar and made her seem drunk. Her sleepiness, in particular, was troubling, as she'd suddenly fall asleep while getting ready for work or preparing meals. This drowsiness would keep her out of work for weeks and suppress her apPetite.

During each visit to the ER, expect the last, doctors diagnosed her with alcohol intoxication. However, "in recent years, she had stopped drinking altogether because of her religious beliefs," doctors wrote in a new report of her case, published Monday (June 3) in the Canadian Medical Association Journal. Her family confirmed that she didn't drink.

Eventually, doctors discovered that the patient's medical history held a clue as to what was causing these bouts of drunkenness.

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Prior to having these drunken episodes, the woman had a five-year history of recurrent urinary tract infections (UTIs), which come back repeatedly and are very difficult to prevent. To treat these, she was prescribed frequent courses of antibiotics, one after the other. 

The woman's doctors suspected that, in addition to clearing her UTIs, these heavy doses of antibiotics wiped out helpful bacteria in her gut. This likely cleared the way for various fungi in the gut to take over. Some of these fungi can ferment carbohydrates, essentially brewing their own alcohol.