"Alarming" numbers of children are being exposed to images of self-harm before they are even teenagers, a study by four youth charities has found.
According to the survey, 60% of 11 to 14-year-olds have shared photographs of people self-harming on social networking sites.
When children from this age group were asked how they responded to such images, more than half said they "felt like hurting themselves afterwards".
The study also suggests that 80% of 18 to 21-year-olds have self-harmed, or know someone who has - prompting experts to warn the findings "beg concerning questions about the relationship between self-harm, children, young people and parts of the online world".
More than 2,000 people aged between 11 and 21 were questioned by ChildLine, YouthNet, selfharmUK and YoungMinds ahead of Self-Harm Awareness Day on 1 March.
Emma Thomas, chief executive of YouthNet, said: "We all have a responsibility to share content and images responsibly online, and to be aware of how what we post might affect others.
"Far more must be done to educate and empower young people, so they can be safer online."
In response to the findings, a Government spokesman said it took the issue of child safety online very seriously - with £150m being invested to help young people who suffer from eating disorders, and those who self-harm.
He added: "The four main internet service providers have committed to giving their customers an unavoidable choice on installing family friendly filters that will protect all devices in the home.
"These allow parents to prevent their children from accessing suicide and self-harm sites, as well as other potentially harmful content."
