Increased recreational ketamine use and subsequent outbreak of urological complications in The Netherlands.

Introduction: Recreational ketamine use has increased in the last decades with incidental reports of urological complications. This study aimed to explore trends in the number of acute intoxications and urological complications from recreational ketamine use in the Netherlands.

Methods: We retrospectively studied data from 2018 to 2024 from inquiries on ketamine toxicity to the Dutch Poisons Information Centre and data from the first outpatient clinic dedicated to ketamine-induced uropathy in the Netherlands at Jeroen Bosch Hospital, 's-Hertogenbosch.

Results: An increase was observed in the number of intoxications with ketamine reported to the poisons centre (from 33 in 2018 to 139 in 2024), in 12 cases (2.4%) urological complaints were reported. The number of patients with ketamine-induced uropathy treated by the outpatient clinic increased from zero in 2018 to 137 in 2024. Long-term and extensive ketamine use (>1 g/day for a median of 35 months, with a median amount of 18 g/week) was associated with urological complaints. Ketamine users in our study were predominantly males in their twenties. Co-exposures were common, 65.1% of acutely intoxicated patients and 72.1% of patients with uropathy reported using other drugs, including alcohol, in addition to ketamine. Fifty-one outpatients developed severe uropathy requiring surgery, ultimately leading to cystectomy and urinary deviation in three cases.

Discussion: This study combines data from a poisons information centre and a dedicated urological ketamine outpatient clinic and describes a large cohort of patients with ketamine-induced uropathy. The extent of complications from chronic recreational ketamine use in the Netherlands only became clear from the data of the urological outpatient clinic at Jeroen Bosch Hospital, 's-Hertogenbosch.

Conclusion: Ketamine-induced uropathy is rising in the Netherlands. Cooperation between poisons centres and medical specialities can enhance toxicovigilance. Increased awareness among potential users and health care providers is pivotal to prevent this from developing into a public health crisis.