Jason Mahr’s eldest son was 13 years old when Mr. Mahr and his wife gave him access to social media, a decision the 44-year-old father of five regretted immediately.

It became “like an addiction,” said Mr. Mahr, a student coach and former youth pastor who lives in Woodstock, Ga. His son was quickly swept up in seeking the approval of others online, Mr. Mahr said. He has since been more deliberate about how and when he lets his younger children start using social media, but backpedaling with his eldest has been difficult.

Recently, the warnings around teens’ social media use have grown particularly loud, as both the U.S. surgeon general and the American Psychological Association have issued reports about the risk of harm to adolescents’ mental health. Yet for many families, that ship has sailed. Survey results from Pew Research found that 95 percent of teens said they had access to a smartphone, while 35 percent said they were using at least one of the top five social media platforms (YouTube, TikTok, Instagram, Snapchat and Facebook) “almost constantly.”

Jean Twenge, a psychologist who has spent years warning about the effects of social media on teenagers’ mental health — and a mother of teens herself — said parents should “be confident in setting some reasonable limits,” but empathized with how challenging that can feel, in the absence of better regulations for children on social media sites. “This is what so many parents are struggling with, and it’s too bad we have to.”

For those looking to walk back their teens’ social media use, these three strategies can help.

1. Come up with boundaries together.

The American Academy of Pediatrics offers a free tool that can help you devise a family media plan, even if that is not something you’ve had as a family before.