Background Workplace bullying has been associated with mental health, but longitudinal studies confirming the association are lacking. This study examined the associations of workplace bullying with subsequent common mental disorders 5–7 years later, taking account of baseline common mental disorders and several covariates.

Methods Baseline questionnaire survey data were collected in 2000–2002 among municipal employees, aged 40–60 years (n=8960; 80% women; response rate 67%). Follow-up data were collected in 2007 (response rate 83%). The final data amounted to 6830 respondents. Workplace bullying was measured at baseline using an instructed question about being bullied currently, previously or never. Common mental disorders were measured at baseline and at follow-up using the 12-item version of the General Health Questionnaire. Those scoring 3–12 were classified as having common mental disorders. Covariates included bullying in childhood, occupational and employment position, work stress, obesity and limiting longstanding illness. Logistic regression analysis was used.

Results After adjusting for age, being currently bullied at baseline was associated with common mental disorders at follow-up among women (OR 2.34, CI 1.81 to 3.02) and men (OR 3.64, CI 2.13 to 6.24). The association for the previously bullied was weaker. Adjusting for baseline common mental disorders, the association attenuated but remained. Adjusting for further covariates did not substantially alter the studied association.

Conclusion The study confirms that workplace bullying is likely to contribute to subsequent common mental disorders. Measures against bullying are needed at workplaces to prevent mental disorders.