The use of ketamine as a recreational drug, particularly among teenagers, has increased dramatically in the past few years in Taiwan. Its effects on the central nervous and cardiovascular systems are well characterized, but an increasing amount of evidence demonstrates its association with urinary tract pathologies. Chronic ketamine use has been associated with severe ulcerative cystitis. Symptoms and signs of long-term ketamine abuse include: hematuria; increased voiding frequency; urgency; bladder pain; dysuria; nocturia; decreased bladder capacity; urothelial ulceration, and eosinophil infiltration. Vesicoureteral reflux and renal function impairment may also occur in heavy ketamine users. How ketamine use produces these symptoms is not clear. Dysregulation of purinergic neurotransmission has recently been found to play a role in the detrusor overactivity in ketamine-induced bladder dysfunction. The goal of treatment is to prevent deterioration of the renal function and indeed offer the possibility of symptom resolution. Currently, ketamine cessation is the only effective treatment modality, but the effect is likely to be dependent on the severity and duration of the abuse. Anticholinergic agents fail to relieve the symptoms induced by chronic ketamine use. Intravesical hyaluronan solution instillation may help improve the symptoms, but more clinical studies are required to provide evidence of the effectiveness. A multidisciplinary treatment team of doctors, psychiatrists, nurses, therapists, and clinicians will facilitate best practice management of patients with ketamine-associated cystitis.