"We found that suicidal thoughts and attempted suicides are significantly related to bullying, a highly prevalent behavior among adolescents," Mitch van Geel told Reuters Health in an email.
Van Geel is the study's lead author from the Institute of Education and Child Studies at Leiden University in the Netherlands.
He said it's estimated that between 15 and 20 percent of children and teens are involved in bullying as the perpetrator, victim or both.
"Thus efforts should continue to reduce bullying among children and adolescents, and to help those adolescents and children involved in bullying," he wrote.
While previous studies have found links between bullying and suicidal thoughts and attempted suicides, less is known about whether the association differs between boys and girls. Also, fewer studies have examined the role of cyberbullying.
For the new analysis, published in JAMA Pediatrics, the researchers searched databases for previous studies published on bullying.
They found 34 studies that examined bullying and suicidal thoughts among 284,375 participants between nine and 21 years old. They also found nine studies that examined the relationship between bullying and suicide attempts among 70,102 participants of the same age.
Overall, participants who were bullied were more than twice as likely to think about killing themselves. They were also about two and a half times more likely to attempt killing themselves.
Image: Sad boy, via Shutterstock