Objectives We aimed to examine longitudinally whether workplace bullying was associated with subsequent psychotropic medication among women and men.

Design A cohort study.

Setting Helsinki, Finland.

Participants Employees of the City of Helsinki, Finland (n=6606, 80% women), 40–60 years at baseline in 2000–2002, and a register-based follow-up on medication.

Primary and secondary outcome measures Workplace bullying comprised questions about current and earlier bullying as well as observing bullying. The Finnish Social Insurance Institution's register data on purchases of prescribed reimbursed psychotropic medication were linked with the survey data. All psychotropic medication 3 years prior to and 5 years after the baseline survey was included. Covariates included age, prior psychotropic medication, childhood bullying, occupational class, and body mass index. Cox proportional hazard models (HR, 95% CI) were fitted and days until the first purchase of prescribed psychotropic medication after baseline were used as the time axis.

Results Workplace bullying was associated with subsequent psychotropic medication after adjusting for age and prior medication among both women (HR 1.51, 95% CI 1.18 to 1.93) and men (HR 2.15, 95% CI 1.36 to 3.41). Also observing bullying was associated with subsequent psychotropic medication among women (HR 1.53, 95% CI 1.25 to 1.88) and men (HR 1.92, 95% CI 1.23 to 2.99). The associations only modestly attenuated after full adjustment.

Conclusions Our findings highlight the significance of workplace bullying to subsequent psychotropic medication reflecting medically confirmed mental problems. Tackling workplace bullying likely helps prevent mental problems among employees.