Serotonin reuptake inhibitors (SSRIs) are commonly used to treat obsessive-compulsive disorder (OCD). In the UK, sertraline and fluvoxamine are the only SSRIs licensed for use in young patients with OCD. There is currently limited evidence suggesting an increased risk of urinary incontinence with SSRI use. Literature in children and adolescents is even more scarce, with only a few published case reports of SSRI-induced urinary symptoms. This case report adds to the pre-existing evidence in support of the previous suggestion on sertraline-induced urinary incontinence.

A 14-year-old girl with a diagnosis of OCD was treated with a combination of cognitive behavioural therapy (CBT) and sertraline, which was gradually titrated in steps of 25 mg fortnightly. There was a noticeable improvement in her OCD symptoms soon after the medication was initiated. However, a few days after sertraline was increased to 100 mg, she started to report urinary incontinence, urgency, and frequency, both daytime and nighttime, which significantly impacted her quality of life. She denied other urinary symptoms or change in fluid intake. Investigations for diabetes mellitus and urinary tract infection were negative. It was therefore concluded that her urinary incontinence was related to an increase in sertraline dosage, and she was advised to take an alternating dose of 75 mg and 100 mg daily. The symptoms resolved shortly afterwards, and sertraline was subsequently titrated up to 150 mg daily without any issues.

Due to its rare encounter, the association between the use of sertraline and urinary incontinence has only been quantified in a single retrospective study with an adjusted risk ratio of 2.76 (95% CI 1.47–5.21). A clear temporal relationship of symptoms, its occurrence after the dosage increase, and rapid resolution after dose reduction confirmed the role of sertraline in the development of urinary incontinence in this case. Consistent with a previous case report, the dose-dependent effect was also implied. This phenomenon might be explained pharmacologically by sertraline's serotonergic activation, which can potentiate neuromuscular cholinergic transmission in the detrusor muscle, and dopaminergic activation, which can stimulate urine micturition. However, the exact mechanism remains unclear.

Although sertraline-induced urinary side effects occur relatively infrequently, clinicians should be aware of and actively look for these side effects, especially in patients who are prescribed SSRIs at higher doses. It is also important to exclude other causes that may contribute to urinary incontinence.