Going forward, doctors should ask young people in this risk group about their Internet use, and the online content they view, the researchers said.
Given that so many youth are online, researchers should also consider ways to use the Internet to help at-risk youth.
"While social media might be useful for supporting vulnerable adolescents, we also find that the Internet is doing more harm than good in some cases," study researcher Kate Daine, a postgraduate researcher at the University of Oxford in the United Kingdom, said in a statement. "We need to know more about how we can use social media as a channel to help young people in distress."
The researchers reviewed 14 published studies on Internet use by teens and young people.
One study of Internet forum posts found that people were less distressed three months after they started posting. Another study found that forums could encourage good behavior, such as seeking help from a doctor.
However, other studies revealed a negative picture of Internet forums. One found that forums may make self-harm seem like a normal or acceptable behavior, and another found that nearly 10 percent of forum posts dealt with methods to carry out or hide self-harm behavior.
About 60 percent of all young people in a different study said that they had researched suicide online in the past. And nearly three-quarters of those who engaged in self-harm said they had researched it online beforehand.
"Rather than concentrating primarily on ways of blocking and censoring such sites, we should think about online opportunities to reach out to people in emotional distress," Joe Ferns, executive director of policy at Samaritans, a charity founded in the United Kingdom that runs a suicide crisis hotline, said in a statement. However, "Where possible, the authorities should use their existing powers to prosecute malicious individuals" who encourage suicide online, Ferns said.