Cyberbullying and "sexting" by young people can lead to depression in later life, warns a psychiatrist.
Natasha Bijlani, from the Priory Hospital, Roehampton, says she expects to see a rise in teens and adults self-harming because of exposure to online and digital abuse.
She says children often fear reporting abuse which can lead to anxiety, depression and stress in adulthood.
The NSPCC says children need help "as early as possible".
"Sexting", when teenagers share explicit photos of themselves with their peers, is seen by some as the "new courtship", she says.
But together with online bullying it can have disastrous consequences, says Dr Bijlani: "The long-term effects of bullying can be prolonged and pervasive.
"Much more focus needs to be given on how best to educate young people about the risks of sending compromising images, and communicating with unknown others online."
She says sexting "seems to have become endemic and we are not sure of the long-term consequences".
'Brink of despair'
Dr Bijlani draws on research that suggests depression and anxiety affect more children than ever before.
According to data from the Health and Social Care Information Centre (HSCIC), emergency admissions for psychiatric conditions rose to 17,278 in 2014, double the number four years previously.
There were 15,668 admissions of young women aged 15 to 19 for cutting, burning or harming themselves compared with 9,255 admissions in 2004.
Recent figures from the Office for National Statistics (ONS) showed one in five 16- to 24-year-olds had symptoms of depression, anxiety or stress.
The Priory Group, which offers mental health services to children and adults, has seen a rise of 12- to 17-year-olds treated for serious depression or anxiety issues, from 178 in 2010 to 262 in 2014.
These young people, she says, would have been the first users of social media.
Peter Wanless from the NSPCC said: "A rising number of children contact ChildLine because they have mental health issues and just as worrying is the lack of executive services to help them.
"We know that some children who have been abused, bullied or relentlessly harassed to send sexual images of themselves sometimes resort to self-harming and others are having their futures jeopardised by depression.
"Whatever the reason, we must tackle the root causes and invest in support that helps them as early as possible.
"If we ignore this problem, we risk leaving a generation on the brink of despair."