Six months prior, the woman had dunked her feet in a tub of water filled with tiny fish called Garra rufa that will eat dead human skin when no plankton are around. The woman assumed at first that she had onychomadesis, however, her dermatologist informed her that onychomadesis was not the reason this was happening.
In the JAMA case, Lipner says with no other explanation for what could have caused the problems with the young woman's toenails, the pedicure seems the most likely culprit.
Fish pedicures are said to leave feet smoother and smelling fresher, however, these claims are "unfounded", according to Lipner, adding there are many risks associated with it.
Writing in the journal JAMA Dermatology, she explained that the freakish beauty ritual first gained traction after people noticed that wild populations of the toothless fish - a member of the carp family native to Turkey - liked to nibble on human skin, and for whatever reason, preferred munching on unsightly psoriasis plaques more than normal tissue.
"While the mechanism of action is not entirely clear, it is likely due to the fish traumatising the nail matrix", Sheri Lipner, an assistant professor of dermatology at Columbia University's Weill Cornell Medicine and the woman's treating doctor, told Gizmodo via email.
She said the case could be the first documented instance of onychomadesis ever caused by fish.
This phenomenon, known to doctors as onychomadesis, usually results in the nail falling off long after an initial event (such as an injury) arrests nail growth.
"I do not recommend fish pedicures for any medical or aesthetic goal", she told Gizmodo.
But while there's no way to know for sure what caused the patient's toenail issues, there have been some concerns about fish pedicures in the past.
Another species of fish, which "grows teeth and can draw blood", is sometimes mistaken for Garra rufa and used in fish pedicures, according to the US Centers for Disease Control and Prevention. There were reports of a patient with a Staphylococcus aureus infection after a fish pedicure. In 2011, the Vancouver Island Health Authority also banned it, saying that there were bacterial risks because the fish could not be sterilized. "It was a bit of a craze people got excited about, and then they moved on to the next thing", said Verner-Jeffreys, who added that the concern surrounding fish spas is not just about human health. According to the CDC, more than 10 US states have banned fish pedicures entirely.
"We will have to wait quite a while to see the outcome", she said.