Mohammed Belal, from the British Association of Urological Surgeons, said ketamine was a hard drug to treat. "With chronic use the bladder becomes extremely inflamed, they have severe pain and then they take even more ketamine because it's a strong analgesic and this leads to a feedback loop where things can deteriorate very rapidly," he explained. "If you stop early the bladder can recover, but if you leave it too late it becomes irreversible." He said the majority of the patients he saw were aged 18 to 25, but some users were even younger. The association has put together a document to help other health professionals spot the signs of 'ketamine bladder'. Dr Belal is calling for more awareness, resources and dedicated clinics to address the "very serious issue" with a "holistic approach". "We also need a further education programme in schools and universities highlighting the severe nature of this and also out in nightclubs and other places where people might take [ketamine]," he added.