Young New Zealanders are reaching out to help when they see people in trouble on social media - but they may be taking on more than they can handle.

A new survey has found that 83 per cent of young Kiwis aged 13 to 24 have seen something on social media that made them worry about someone else's safety, and 72 per cent have tried to do something to help.

But the Graeme Dingle Foundation, which commissioned the survey, says we need to do more to help young people to cope with what they see on social media and to set boundaries when they get involved.

"What worries me is that when you are very young it's very hard to carry that weight on your shoulders and to know when enough is enough," said the foundation's research manager Julie Moore.

"We teach them internet safety - not to give out personal information online. But what about their mental health?"

The 509 young people who were surveyed online by Nielsen reported both positive and negative effects of social media. Most (88 per cent) said they had connected via social media with people who have made them "feel really positive" about themselves, but 79 per cent have also seen posts that made them "feel negatively about [their] body image, social situation or background".

Ngāruawāhia High School head student Tommy Goodwyn-Archer, 17, said he intervened when he saw another student threatening a friend on Instagram and Facebook Messenger in a dispute over not giving someone a lift to a beach late last year.

"He posted one photo of one guy holding another guy in a headlock, it was all bloody and stuff, and it had really angry music, lyrics that were really angry. I knew that they wanted to fight him [his friend]," he said.

"I told him [the offender] to stop, and then it all piled on to me."

He told teachers about it and the teachers talked to the two offenders "within five minutes". It was the last week of school and one offender was leaving school anyway and was told to leave immediately.

The other one had planned to come back to school this year but was also told to leave.

"It carried on going a little bit so I ended up going to the police about it," Tommy said.

"I got an email not long ago saying they are still looking into it and to contact them if I wanted them to pursue it, but it's died down now."

However, when he saw someone he didn't know so well being abused on Instagram recently, he stayed out of it.

"I had just got over that big incident and I didn't want another one," he said. "I did see other people getting involved and the guy was saying, 'They're next.'"

Jean Andrews, a counsellor at Taieri College in Mosgiel who represents schools on the NZ Association of Counsellors executive, said she dealt "regularly" with young people disclosing on social media that they wanted to self-harm or die.

"I have desperate parents ringing me and people coming to see me, and I'm following up with the parents and sometimes with the police," she said.

"Sometimes I ring the police direct and send them round to the young person, and I have actually saved lives by doing that. They have overdosed and gone into cardiac arrest, and we have got there within minutes, basically."

Youthline chief executive Shae Ronald said young people who were concerned about a friend on social media could report issues to Instagram or Facebook, which can refer people to agencies such as Youthline.

She is encouraged that young people are reaching out to support each other.

"It's a myth that asking how someone is is going to make it worse. We always encourage people to ask," she said.

"Then, depending on the situation, if someone else is required to deal with it, it's always about referring them into services that can support them."

Instagram was the most popular social media platform in the Nielsen survey, used by 77 per cent of 13-to-24-year-olds, beaten only by YouTube (87 per cent), which is used mainly for watching videos rather than posting new material.

The next most popular platforms were Facebook (76 per cent), Snapchat (62 per cent), Pinterest (25 per cent), Twitter (21 per cent), the Chinese-owned video sharing platform TikTok (8 per cent) and the dating platform Tinder (also 8 per cent).

• Tomorrow: Sexting rings alarm bells.

Positives and negatives

• 88 per cent of young Kiwis aged 13-24 have "connected with a person or group that made you feel really positive about yourself".
• 80 per cent have "found some information or people that helped you deal with some issues you were going through".
• 75 per cent have "got involved with an online group that helped you share your ideas or creativity".

BUT:

• 79 per cent "saw posts online that made you feel negatively about your body image, social situation or background".
• 81 per cent have "been worried about the amount of time you spend on social media".
• 83 per cent "saw or read something that made you worried about the safety of someone else".

Source: Graeme Dingle Foundation.