We found highly increased risks of future mental illness and suicide among young adults after self-harm. A history of a mental disorder was an important indicator of long-term adverse outcome. Clinicians should consider the substantially increased risk of suicide among self-harm patients with psychotic disorders.

This study highlights the strong association of suicide attempts with future marginalization from the labour market, particularly for outcomes that are based on a medical assessment. Studies that focus only on unemployment may largely underestimate the true detrimental impact of suicide attempt on labour market marginalization.

Violent method and mental disorder increase the 1-year suicide risk in young male self-harm patients. Further, violent method increases suicide risk within 1 year in all age and gender groups except the youngest females. Repeated self-harm may increase the long-term risk more in young patients. These aspects should be accounted for in clinical suicide risk assessment.