Heavy recreational ketamine users can develop a specific, well-documented bladder injury. The drug’s own metabolite damages the cells lining the urinary tract directly, and in severe, long-term cases it can scar the bladder down to a fraction of its normal capacity, sometimes requiring surgery. That’s settled science in urology. What’s far less settled is whether the much lower, much less frequent doses used to treat depression carry any meaningful version of that same risk, and a systematic review published last year suggests nobody has checked closely enough to know.
What the review found
A team at King’s College London, led by Jess Kerr-Gaffney, pulled together every clinical trial and observational study that used ketamine to treat a psychiatric condition and separately reported on urinary or bladder symptoms. They found 27 studies, most of them in depression. Urological symptoms showed up in anywhere from zero to about a quarter of patients, and where researchers measured urinary function directly rather than just asking patients how they felt, those measurements didn’t show a meaningful change from before treatment to after. On the surface, that’s reassuring: nowhere near the injury rates seen in people using ketamine recreationally, often at much higher doses, far more frequently, for years.
Why the reassurance doesn’t fully hold up
Only 15 percent of the studies in the review were rated as low risk of bias, meaning the other 85 percent had real weaknesses in how they were designed or reported that could hide a problem or make the drug look safer than it is. Most of the studies didn’t run long enough to test what happens with long-term treatment, the exact scenario now becoming common as ketamine and esketamine get used repeatedly for depression, chronic pain, fibromyalgia, and cognitive impairment in older adults. And many studies simply didn’t watch for bladder symptoms in any structured way. A patient wasn’t asked directly and regularly about urinary symptoms; researchers just noted whatever came up on its own. That’s a different, much weaker kind of safety monitoring than a dedicated bladder-symptom questionnaire administered at every visit.
What a real case looks like when this gap goes unaddressed
A separate case report, published in Frontiers in Pediatrics, describes a child who developed hemorrhagic cystitis, bleeding and inflammation of the bladder, after 16 days of continuous high-dose intravenous esketamine given for a severe seizure emergency, not depression. The child’s symptoms resolved after the dose was tapered and the child was treated with urine alkalinization for twelve days. The case isn’t about psychiatric treatment specifically, but the authors make a point directly relevant to it: adult data on esketamine and bladder symptoms exists, roughly 1 to 3 percent of adults on long-term intranasal esketamine report urinary symptoms, but pediatric data on intravenous ketamine-class drugs and bladder injury barely exists at all. The same authors note children’s bladders are structurally less mature than adults’, with weaker protective barriers, a plausible biological reason kids could be more vulnerable to this specific injury, not just an assumption carried over from adult data.
Why this matters more now than it did five years ago
Ketamine and esketamine started as short-term, closely monitored treatments. They’re increasingly being used as repeated, sometimes indefinite therapy, exactly the pattern most associated with bladder injury in the addiction literature this same drug class is drawn from. A monitoring gap that was a minor footnote when ketamine treatment meant a handful of doses over a few weeks becomes a real clinical and regulatory question when treatment means an infusion every few months for years. Any company pursuing a new indication or a label expansion for repeated ketamine dosing should expect this exact question, not urgently answered by the studies that already exist, but urgently relevant, to come up in regulatory review.
How to close this gap
Bladder symptoms need to be tracked the same deliberate way depression symptoms are, a standard questionnaire, asked at every visit, in every trial testing repeated ketamine or esketamine dosing, not left to whatever a patient happens to mention. Trials also need to run long enough to catch an injury that, based on the recreational-use literature, tends to develop over months or years of exposure rather than after a handful of doses. Neither of those two changes would be difficult or expensive to add to a trial protocol. The bigger obstacle is that most of the studies already completed weren’t built that way, and there’s no simple way to go back and fix that after the fact.