A huge rise in recreational ketamine use will mean more cases of a serious bladder condition, a new report warns.
Drug-checking group Know Your Stuff found ketamine use at festivals in Aotearoa had jumped from just four cases in 2016-17 to 186 in 2020-21.
Medical professionals said that had led to an increase in a dangerous side effect called ketamine cystitis.
Christchurch Hospital urologist Dr Frank Kueppers said research found it was a problem overseas and it was "something that especially primary care physicians need to know".
The symptoms may appear similar to a urinary tract infection, but could become far more serious, he said.
"So there have been reports on people who had their bladder surgically removed, and there was a significant number of people who really needed major surgery to fix the problem."
Kueppers co-authored a report on ketamine cystitis, which was published in the New Zealand Medical Journal, to raise awareness in the medical community.
It noted that the more ketamine someone used, the worse the potential symptoms were.
For one woman who suffered from the condition, and wanted to stay anonymous, the pain was intense.
"I've got a fairly high pain threshold, so I didn't really notice things going badly until I couldn't stand up properly. Just intense pain and nausea. I wanted to vomit but couldn't because I didn't have anything in my stomach."
She was prescribed ketamine for pain relief, and was taking about 425mg, three times a week at the peak of her use.
She did not think many people who were prescribed the drug, or used it recreationally, were aware of the potential health risks.
"It's sort of not really widely known and because people aren't open with their doctors about their drug use, they'll come in and present it as a UTI."
It did not help that ketamine was an anaesthetic, which numbed some of the pain of any bladder issues, she said.
New Zealand Drug Foundation principal science advisor Emily Hughes said ketamine use shot up during Covid-19 lockdowns.
"When people were at home and possibly looking for a substance that provided a different effect than what people would usually take ... like MDMA that people are more likely to use in a partying setting."
The drug was heavily used in social settings, she said.
The report suggested the best way for patients to manage the condition was to stay away from ketamine for as long as possible, but Hughes said that was not realistic for all drug users.
"In a lot of cases, our best advice is - you may not be able to completely stop using it, but at least try to take a break or reduce your dose, just to give your body a break."
Hughes encouraged anyone experiencing symptoms to see their doctor, even if they were not comfortable disclosing their drug use.
Symptoms to look out for included discomfort or difficulty while urinating, or pain in the lower back.
