Ketamine was used recreationally for decades, by some very heavy users at that, before any reports of bladder damage started to surface. It is far more likely that a by product of clandestine ketamine synthesis causes bladder damage, than ketamine actually causing it. Most ketamine is diverted from pharmacies, but at least some percentage of it is clandestinely manufactured. One friend had Chinese synthesized ketamine analyzed and it was only 80% pure, versus diverted pharmaceutical ketamine which is 99.99% pure unless it is cut. Ketamine may cause bladder damage in a very small percentage of users with the recently reported cases being due to its increase in popularity, or it could be a by product of clandestinely synthesized batches, but when a drug has been used heavily for decades before the first reports of it causing bladder damage surface, it really must make you question things.