More than 11,000 cases of self-harm presented at hospitals in Ireland in 2014.
The figures from the National Suicide Research Foundation are being released as part of a new campaign to raise awareness about the issue.
The Know Self Harm campaign is being launched today by SpunOut.ie and will challenge common misconceptions while providing information and support.
Sarah Singleton from the youth website had some advice for people who self-harm or know someone who does.
Ms Singleton said: "I think to try and listen, non-judgementally, to what they have to say about self-harming and to not try to be too scared if someone tells you that you self-harm.
"Also, people could look at the content on our website, services are out there and ways that they could help themselves and get help from a professional."