Instagram is rated as the worst social media platform when it comes to its impact on young people's mental health, a UK snapshot survey suggests.
The poll asked 1,479 people aged 14-24 to rate which of five popular social media platforms had the most negative effect on their users.
They were asked to score each platform on issues such as anxiety, depression, loneliness, bullying and body image.
Mental health charities urged companies to act to increase users' safety.
'Inadequacy and anxiety'
The Royal Society for Public Health study says social platforms should flag up heavy social media use and identify users with mental health issues.
The RSPH report warns that "social media may be fuelling a mental health crisis" in young people.
It can also be used as a tool for good, the report said, and companies should be doing their best to make platforms a safe place to be.
About 90% of young people use social media - more than any other age group - so they are particularly vulnerable to its effects, although it is not clear what these are on current evidence.
'Deep depressive episode'
Isla is in her early 20s. She got hooked on social media as a teenager when going through a difficult time in her life.
"The online communities made me feel included and that I was worthwhile.
"However, I soon began to neglect 'real life' friendships and constantly spent all my time online talking to my friends there.
"I fell into a deep depressive episode aged 16, which lasted for months and was utterly horrible.
"During this time social media made me feel worse, as I would constantly compare myself to other people and make myself feel bad.
"When I was 19, I had another bad depressive episode. I'd go on social media, see all my friends doing things and hate myself for not being able to do them, or feel bad that I wasn't as good a person as them."
Social media has also been a positive in Isla's life.
"I have blogged a lot about mental health and I'm quite open about it and have good conversations with people about it.
"I find it gives me a platform to talk and talking with people is something I find imperative to my own health.
"The online friends I made five or six years ago I'm still friends with to this day and have met many of them in person."
The online survey asked participants a series of questions about whether YouTube, Instagram, Snapchat, Facebook and Twitter had an impact on their health and well-being.
Participants were asked to score each platform on 14 health and well-being issues.
Based on these ratings, YouTube was considered to have the most positive impact on mental health, followed by Twitter and then Facebook.
Snapchat and Instagram were given the lowest scores overall.