While social media use by teens is near ubiquitous, the U.S. Surgeon General is warning that the mental health impacts are still not fully known—and has called on tech companies to “take immediate action to mitigate unintended negative effects.”

Dr. Vivek Murthy noted that while children under 13 are technically banned from signing up for services like TikTok, Snapchat, and more, children have been able to easily join and bypass limitations. Up to 95% of kids between the ages of 13 and 17 report using a social media platform, with more than a third saying they use social media “almost constantly,” according to a new report from the Surgeon General.

Acknowledging that more research is necessary and that there could be some benefits for adolescents, Murthy warned “there are ample indicators that social media can also have a profound risk of harm to the mental health and well-being of children and adolescents. At this time, we do not yet have enough evidence to determine if social media is sufficiently safe for children and adolescents.”