From: https://www.popsugar.com/moms/13-Reasons-Why-Parent-Guide-43401220

1. It opens the floor for some heavy conversations. You may not feel ready to talk to your child about suicide, sexual assault, and depression, but open communication and education about mental illness is so important in their high school years and the series provides an opening for you to discuss each issue before, during, and after you watch (and to note, Netflix warns you before a few of the more difficult episodes to let you know what's ahead).
2. Although it will seem like the least of your worries considering the aforementioned topics, there's plenty of swearing. F*ck, sh*t, asshole . . . all of 'em.
3. The emotional effects of the series may be hard to process. Whether your teen has first-hand experience with bullying, social anxieties, or depression or not, it's undeniable that the feelings this series provokes are strong and lasting. Your teen may feel particularly emotional upon viewing, more so with each episode, so encourage open communication about their feelings along the way.
4. The bullying is sometimes subtle, sometimes over-the-top. When talking to your teen about bullying and cyberbullying in reference to the series, it's important to note that sometimes the events Hannah references as bullying are subtle, but clearly had lasting effects on her. Discuss with your teen the power of their words and actions, as well as what it means to be the type of person who stands up for themselves and their friends against bullies.
5. Hannah seems to take pleasure in the guilt her tapes would cause. Although each person on the tapes was in the wrong in Hannah's opinion, she makes it clear in her recordings that the reason she made them to be heard after it was too late to save her was to make everyone feel guilty for what they'd done. It's important to discuss with your teen why reciprocation and revenge when it comes to bullying can in and of itself be considered bullying.
6. Sexual assault isn't just implied; you see it.From a classmate of Hannah's feeling free to grab her behind in a corner store to multiple instances of rape, the series doesn't hold back. Is it uncomfortable to see? Yes. Is it extremely important and powerful? Absolutely.
7. Hannah's suicide is ultimately shown. We don't want to spoil anything for you, but the last episode does show Hannah's suicide. How she does it, where she does it, and everything in between. It is extremelygraphic, impossibly difficult to watch, and emotionally heavy