In medicine, ketamine is used as an anesthetic. In clubs, where it's better known as "special K," ketamine is snorted, or sometimes injected; users say the drug creates feelings of euphoria and being "out of your body."

Ketamine abuse is on the rise in many countries. 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 side effects don't stop there, however. Among the others are urinary tract symptoms, like pain in the lower belly, painful urination, blood in the urine and bladder-control problems.

But until now, there has been no estimate of how common those side effects may be.

In the new study, UK researchers found that of 1,285 young adults who said they'd abused ketamine in the past year, 27 percent had developed urinary tract symptoms.

And the heavier the dose or more frequent the use, the more likely people were to have symptoms.

The findings give an idea of the prevalence of urinary symptoms among ketamine abusers, said Angela M. Cottrell, a researcher at the Bristol Urological Institute in the UK who worked on the study.

It's not clear how the rate compares with that among young people in general, Cottrell told Reuters Health by email.

But, she and her colleagues say, the findings confirm an association between ketamine and urinary problems.

"The take-home message is that regular ketamine use can lead to severe urinary symptoms," Cottrell said.

CLUB MUSIC MAGAZINE SURVEY

The findings, reported in the British Journal of Urology International, are 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 ever used ketamine, and 1,285 -- or a third of the whole group -- said they'd used it in the last year.

The researchers found that of all past-year users, 17 percent had symptoms of dependence on ketamine -- like 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, Cottrell's team found, 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.

In this 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."

SOURCE: bit.ly/HgoAq7 BJU International, online March 14, 2012.

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