Many people who use the club drug ketamine – known as “special K” – may risk abdominal pain, bladder control problems and other urinary tract issues, and the heavier the dose or frequency of use, the more likely the problems, according to a UK study.

The study, which appeared in the British Journal of Urology International, found that of 1,285 young adults who said they’d abused ketamine in the past year, 27 percent had developed urinary tract symptoms.

In medicine, ketamine is used as an anesthetic. In clubs, where it’s better known as “special K,” ketamine is snorted or sometimes injected, with users saying it creates feelings of euphoria and being “out of your body.”

Related: Ketamine: A miracle antidepressant?

Ketamine abuse is on the rise in many countries, and repeated use has been linked to mental problems such as hallucinations and impaired memory, thinking and concentration. It can also cause high blood pressure.

The study, led by Angela Cottrell, a researcher at the Bristol Urological Institute, looked at the prevalence of urinary tract symptoms such as pain in the lower belly, painful urination, blood in the urine and bladder-control problems.

“The take-home message is that regular ketamine use can lead to severe urinary symptoms,” Cottrell said, although she did say it was not clear how the rate of urinary problems among ketamine users compared to young people in general.

The findings were based on an online survey promoted by a UK club-music magazine called “MixMag.”

Of 3,806 young people who responded, half said they’d tried it at least once, while 1,285 – or a third of the whole group – said they’d used it in the last year.

The researchers found that among all of the past-year users, 17 percent had symptoms of ketamine dependence such as wanting, but failing, to cut down on the drug. Not surprisingly, they tended to take the drug in bigger doses, and more often, than other users.

In general, the odds of urinary problems and abdominal pain went up as people’s ketamine doses climbed, and with more frequent use.

Those symptoms often seem to go away once the ketamine abuse stops.

For the study, 251 survey respondents described their experience. half said they’d stopped using the drug and their symptoms had improved. Another 43 percent still had urinary problems, but were also still abusing ketamine.

Then there was the 4 percent who said their urinary problems were getting worse even though they were off ketamine.

“There may be a stage where irreversible damage may occur,” Cottrell said. “However, little is known about this.”