A rising number of young people in West Yorkshire are suffering irreversible bladder problems as a result of using the drug ketamine.
The drug damages the cells lining the bladder, which leads to a reduction in bladder capacity. There has been a rise in the number of people needing treatment for Ketamine Bladder Syndrome.
Toni Williams, specialty registrar for public health, said: "Up until a few years ago this condition was almost unheard of; however in the last few years we have seen an increasing number of cases in West Yorkshire.
"In Leeds alone, we are seeing a new case requiring hospital treatment on average every three to four months."