To assess the risk for suicide attempt before, during and after treatment with isotretinoin for severe acne. Retrospective cohort-study linking a named patient register of isotretinoin-users 1980–1989 to the hospital discharge- and cause of death registers 1980–2001.

5,756 patients prescribed isotretinoin for severe acne observed for 17,192 person-years before, 2,905 on and 87,120 after treatment. Main outcome measures Standardized Incidence Ratio (SIR): observed divided by expected number of suicide attempts standardized by sex, age and calendar-year, calculated up to three years before, during and up to 15 years after end of treatment.

128 patients were hospitalized for suicide attempt. During the year preceding treatment, the SIR for suicide attempt was elevated: 1.57 (95% CI 0.86 to 2.63) for all (including repeat) attempts, and 1.36 (95% CI 0.65 to 2.50) counting only first attempts. For all and first attempts, SIRs during and up to 6 months after treatment was 1.78 (1.04 to 2.85) and 1.93 (1.08 to 3.18) respectively. The observed number of attempts was close to the expected during the 15 years of follow-up. The number needed to harm was 2,300 new 6-months’ treatments per year, for one additional first suicide attempt to occur.

An increased risk for suicide attempt was observed up to six months after treatment with isotretionoin, which motivates a close monitoring of patients regarding suicidal behaviour for up to a year after treatment has ended. The risk for suicide attempts were rising already before treatment, and therefore, an additional risk due to the isotretinoin treatment cannot be established.