A new study shows the number of Ontario teens visiting a hospital emergency department for self-harm has more than doubled between 2009 and 2017.

The study, published this week in the Canadian Journal of Psychiatry, also found the rates of visits by teens aged 13 to 17 for mental health problems rose 78 per cent during that time.

It says the increases in both types of visits were even more pronounced among teenage girls.

The study was conducted using data on emergency department visits from the Canadian Institute for Health Information.

The research notes that teens who intentionally hurt themselves through poisoning or injury are at risk for repeated self-harm or suicide.

The authors say more research is needed to shed light on the reasons for these increases, adding some social shifts that occurred during the study period may have played a role.