The clip will autoplay ahead of the first episode in each season.
"13 Reasons Why is a fictional series that tackles tough, real-world issues, taking a look at sexual assault, substance abuse, suicide and more," the stars say in the video.
"By shedding a light on these difficult topics we hope our show can help viewers start a conversation. But if you're struggling with these issues yourself, this series may not be right for you, or you may want to watch it with a trusted adult.
"If you ever feel you need someone to talk with, reach out to a parent, a friend, a school counselor or an adult you trust," they advise.
"Call a local help line or go to 13reasonswhy.info because the minute you start talking about it, it gets easier."
Netflix previously added title cards with advisory warnings that played before Season 1 episodes.
The streaming site said in a tweet Wednesday that the show has "changed the lives" of some viewers by encouraging them to share their stories.
"13 Reasons Why" is based on the Jay Asher book of the same name. The series will return for a second season this year.
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