Fish pedicures have become an increasingly popular method of grooming one’s toes, especially for travelers visiting places like Japan and Turkey, but it turns out that they might not be quite as innocuous as we thought. Six months after soaking her feet in a tub of water filled with tiny Garra rufa fish, a young woman’s toenails started separating from her toes. During these pedicures, the fish eat the dead human skin, but in this instance — and potentially many others — it’s believed that the biting caused a delayed separation of nail and skin.

Dr. Shari R. Lipner, in a report published in the JAMA Dermatology journal, describes the phenomenon (called onychomadesis) as “a relatively common physical examination finding,” with no other medical history to account for the patient’s abnormal toenails. Lipner believes that the patient’s issue stemmed from the physical impact of the fish biting her nails.

This isn’t the first time infections have resulted from fish pedicures. There have been several other instances reported, though experts say it might be due to lingering microbes from whomever’s feet were in the bath last (rather than directly because of the fish themselves).

While infections due to fish pedicures are relatively uncommon, fish pedicures have nonetheless been banned in at least 10 US states. The Garra rufa treatment, in particular, is not considered a standard medical practice. “I would be highly surprised,” said Lipner, “if you found any dermatologist who recommends Garra rufa pedicures.”

H/T: CNN