Using the club drug ketamine three times a week for two years can impair bladder function, Hong Kong researchers report.

Regular, long-term use of ketamine, also known as “Special K,” can lead to symptoms such as painful urination, having to urinate frequently and pelvic pain, according to Reuters. These symptoms can last for up to a year or more after a person stops using the drug, the researchers write in the Journal of Urology. The study included 66 teens and young adults.

Ketamine is an anesthetic that is used in human anesthesia and veterinary medicine. Reuters notes that ketamine abuse is increasing in many countries. The drug can cause hallucinations, delirium, amnesia, impaired motor function, high blood pressure, depression and potentially fatal respiratory problems.