Children as young as 2 are accessing social media, service practitioners from across the country have suggested – leading to fears that more young people are becoming addicted.
More than 60 per cent of professionals who have dealt with vulnerable children in the past six months indicated that they were worried about under-fives using social networks, not only because of exposure to inappropriate content but also how it may affect their communication skills.
According to a report by Barnardo's, which gathered insight from 80 practitioners across more than 30 services in the UK, experiences that could have an impact on young people's mental health and well-being peak between the ages of 11 and 15.
Half said children between 5 and 10 they had dealt with have been exposed to unsuitable or harmful content, rising to 78 per cent among 11- to 15-year-olds.
The same age group reported prominent incidents of cyberbullying (80 per cent), sharing of personal content (87 per cent), online grooming (78 per cent) and family tensions due to social media use (78 per cent) in the last six months.
The concerns come after the government published a White Paper on online harms, proposing strict new rules be introduced that require firms to take responsibility for their users and their safety, as well as the content that appears on their services.
Child sexual abuse and exploitation, harassment, cyberstalking, and hate crime are among a list of areas the government wants to be legally overseen by an independent regulator, after deciding that social networks and web giants can no longer be relied on to self-regulate.
As the Conservative Party looks for a new leader, the children's charity has warned the country's next prime minister not to lose sight of protecting the most vulnerable in society.
"Although the internet offers incredible opportunities to learn and play, it also carries serious new risks from cyberbullying to online grooming," said Javed Khan, chief executive of Barnardo's.
"And, as our new report shows, these risks can have a devastating impact on the lives of the UK's most vulnerable children.
"Recently, the government has proposed welcome changes that would help regulate the internet and make it safer for children.
"It's vital that the next prime minister keeps up the momentum and focuses specifically on protecting the most vulnerable.
"Our new report also calls for more research to help us understand the impact of social media on children's mental health; high-quality education for children, parents and professionals; and a focus on well-being in every school.
"Children today see the internet as a natural part of their world.
"Our job as a society is to make sure children are protected online just as they are offline."
Bernadka Dubicka, chairperson of the child and adolescent faculty at the Royal College of Psychiatrists, said the findings reflect what she sees on the front line every week.
"The levels of self-harm and suicide attempts following cyberbullying found in this report are deeply concerning and is another wake-up call for social media companies to do more to protect young people online," she said.
"The government must act on the proposals in the NHS Long Term Plan and deliver the additional funding needed to increase the mental health workforce and improve services for our children and young people.
"The college supports Barnardo's in its call for government-funded research into the impact of social media on our children and young people, including the most vulnerable in our society."