There needs to be a "very serious conversation" with Netflix about its handling of the newest season of 13 Reasons Why, the Chief Censor says.
The second season of the controversial drama premiered last week, depicting scenes of suicide, drug use, gang rape and self harm.
Teenagers are taking to Twitter to say how traumatised they are by the show.
Prior to its release, the Office of Film and Literature Classification created a new rating for the show - RP18 - meaning any viewer under the age of 18 must be supervised by a parent or guardian.
Netflix also placed warning messages before certain episodes that contained potentially traumatic content.
However, Chief Censor David Shanks told RNZ's Morning Report that the warnings Netflix had included were inadequate.
"One of the things I was saying to Netflix was 'this is primarily a series about rape, that is a dominant theme, you need to say that to people really clearly."
Mr Shanks said the show needed more on-screen warnings about the graphic content.
"[Netflix] need to learn from this experience and we're learning from it as well.
"I think there's a very serious conversation that needs to be had with Netflix and they are listening to us about - 'look, this didn't work, how can we make this clearer and more effective in terms of discharging your duty of care to your consumers to advise them about what is in this product."
He said explicit warnings about graphic scenes were more important than preventing spoilers.
"When you're talking about this type of impactful content, yes you need to let go of the spoilers type reservation and I think we need to be really clear with parents and caregivers in particular to be really quite emphatic and direct them to 'look this happens at this point in this show - you want to check this out'."
He also said the classification and warnings did not show up on certain devices on launch.
"[It has] a different warning and, in fact, a different age classification if you accessed it via an Android phone as I recall," he said.
"And for a period it seemed that if you accessed the show through a DVD device that was WI-FI connected into your television you might not get a warning at all."
Mr Shanks said he had contacted top officials at Netflix, who were working to fix the issue.
Concerns have also been raised about the final episode, which depicts the graphic gang rape of a teenage boy.
Before the episode, Netflix runs a warning which reads: "The following episode contains graphic depiction's of sexual assault and drug abuse."
Mental Health Foundation chief executive Shaun Robinson said he had received several complaints from viewers who felt the warning was grossly inadequate in comparison to what was shown.
Many young viewers also took to Twitter to share their feelings.
"The bathroom scene in the last episode of 13 Reasons Why season [two] needs to be taken down, I wish it was less graphic... I'm feeling disgusted and distressed at this point. I can't sleep because of this, the image can't leave my head," said one user.
"I know it's a reality and things like that do happen but that scene is gonna stick with me. I feel ill and I can't get that scene out of my head, I'm just about ready to throw up," said another.
Mr Robinson said he knew of 12-year-olds who had viewed the entire season from start to finish.
"We have to remember that while Netflix says this is R18, there is nothing to stop much younger people viewing this, and viewing it in a binge intensifies the potential damage," he said.
"I have a 12-year-old daughter and I know amongst her friendship group watching 13 Reasons Why is very, very popular and... I do talk to my daughter about issues such as sexual violence but I don't want her seeing a scene like that."
It was important for parents to research the show and openly discuss it's themes with their children, he said.
Where to get help
Lifeline: 0800 543 354 or text HELP to 4357
Suicide Crisis Helpline: 0508 828 865 / 0508 TAUTOKO (24/7). This is a service for people who may be thinking about suicide, or those who are concerned about family or friends.
Depression Helpline: 0800 111 757 (24/7)
Samaritans: 0800 726 666 (24/7)
Youthline: 0800 376 633 (24/7) or free text 234 (8am-12am), or email email@example.com
What's Up: online chat (7pm-10pm) or 0800 WHATSUP / 0800 9428 787 children's helpline (1pm-10pm weekdays, 3pm-10pm weekends)
Kidsline (ages 5-18): 0800 543 754 (24/7)
Rural Support Trust Helpline: 0800 787 254
Healthline: 0800 611 116
Rainbow Youth: (09) 376 4155
This story was first published on RNZ and is used with permission.