The Censor's Office has created a new classification especially for a Netflix series, which means teenagers must watch it with a parent or guardian.
13 Reasons Why was released a month ago and contains graphic depictions of rape and suicide.
The series has divided opinion about whether it was appropriate for young people.
The Mental Health Foundation said the show never should have been released, because it put young people at risk, while teachers and teenagers spoken to by RNZ said it raised issues worth talking about.
After reviewing the show and speaking to experts, the Censor's office has created the RP18 classification.
Deputy Chief Censor Jared Mullen said if teenagers wanted to watch 13 Reasons Why, they needed to be able to discuss the issues raised with a responsible adult.
"We know that kids know they're not supposed to watch something and still do, the key thing is that teens and parents have the information make a decision, that's really what the classification is about."
He told Morning Report parents and teens did not necessarily need to watch the show side by side.
"Teens did tell us that there are some scenes in this show that they'd be embarrassed to watch with their parents," he said.
"Parents can watch this on their own device at the same time ... because this is a streamed show.
"All that's really essential is that they know their kids are watching it, that they watch it at the same time or ahead of their kids ... and most importantly, they talk to their children about the themes in the show."
Mr Mullen said the new classification may be used on other similar shows in the future.
"We have used RP13 and RP16, for example, where parental guidance is required for those ages. But RP18 is something we haven't had to use before, but if this show is any indication, we may well need to use this classification again.
"The reason it's RP18 is because there is a risk of harm right up to until the age of 18 with this show, and in fact the risk of suicide and suicidal behaviour increases for 16-17 year olds, relative to other age groups, so we thought that guidance was essential, right up to the age of 18 in this case."
Where to get help relating to suicide and mental health:
If it is an emergency and you feel like you or someone else is at risk, call 111.