The U.S. surgeon general, Dr. Vivek Murthy, announced on Monday that he would push for a warning label on social media platforms advising parents that using the platforms might damage adolescents’ mental health.

Warning labels — like those that appear on tobacco and alcohol products — are one of the most powerful tools available to the nation’s top health official, but Dr. Murthy cannot unilaterally require them; the action requires approval by Congress.

The proposal builds on several years of escalating warnings from the surgeon general. In a May 2023 advisory, he recommended that parents immediately set limits on phone use, and urged Congress to swiftly develop health and safety standards for technology platforms.

He also called on tech companies to make changes: to share internal data on the health impact of their products; to allow independent safety audits; and restrict features like push notifications, autoplay and infinite scroll, which he says “prey on developing brains and contribute to excessive use.”

In an interview, Dr. Murthy said he had been deeply frustrated by the platforms’ reluctance to do so.

“I don’t think we can solely rely on the hope that the platforms can fix this problem on their own,” he said. “They’ve had 20 years.”

He said that he was “quite optimistic” that legislators will put forward a bill requiring a warning label, which he envisioned would appear regularly on screens when people use social media sites.

The push for a warning label sets up a battle between the Biden administration and the tech industry, which has sued several states for laws on social media.

Technology companies are likely to argue that the science on the harmful effects of social media is not settled. They will also invoke free speech law, arguing that the government cannot force companies to carry a product warning, which is sometimes described as “compelled speech.”

“Legally speaking, it’s no different from a Trump administration surgeon general declaring there needs to be a warning label on mainstream media because he deems it to be fake news,” said Adam Kovacevich, chief executive of Chamber of Progress, a tech lobbying firm. “It’s all the same abuse of government’s power to infringe on speech.”

That challenge may find a sympathetic ear in U.S. courtrooms, with a cohort of judges who show less deference to public health regulations than their predecessors did, said Claudia E. Haupt, a professor of law and political science at Northeastern University School of Law.

For more than a decade, cigarette companies have successfully used a First Amendment argument to fend off a requirement that they print a graphic photograph of diseased lungs on tobacco products, she said.

TikTok did not immediately respond to a request for comment on the surgeon general’s proposal. Spokespeople for YouTube and X declined to comment.

The surgeon general’s call to action received support from two senators, Richard Blumenthal, Democrat of Connecticut, and Marsha Blackburn, Republican of Tennessee, the authors of the Kids Online Safety Act, which would require platforms to take a range of steps to protect minors on social media but does not include warning labels.

“We are pleased that the Surgeon General — America’s top doctor — continues to bring attention to the harmful impact that social media has on our children,” a joint statement from the two senators said.

Past warning labels have had significant effects on behavior. In 1965, after a landmark report from the surgeon general, Congress voted to require all cigarette packages distributed in the United States to carry a warning that using the product “may be hazardous to your health.”

Thus began a 50-year decline in smoking. When the warning labels first appeared, around 42 percent of U.S. adults were daily cigarette smokers; by 2021, that portion had dropped to 11.5 percent.

There is fierce debate among researchers about whether social media is behind the crisis in child and adolescent mental health. In his new book, “The Anxious Generation,” the social psychologist Jonathan Haidt points to the rise of smartphones in the late aughts as an inflection point that led to a sharp increase in suicidal behavior and reports of despair.

Other experts say that, while the rise of social media has coincided with declines in well-being, there is no evidence that one caused the other, and point instead to factors like economic hardship, social isolation, racism, school shootings and the opioid crisis.

In an essay published in The New York Times opinion section on Monday, Dr. Murthy pointed to research showing that teens who spent more than three hours a day on social media faced a significantly higher risk of mental health problems, and that 46 percent of adolescents said that social media made them feel worse about their bodies.

U.S. teens are spending an average of 4.8 hours per day on social media platforms like YouTube, TikTok and Instagram, according to a Gallup survey of more than 1,500 adolescents released last fall.

In an interview last month, Dr. Murthy said he had repeatedly heard from young people who “can’t get off the platforms,” often finding that hours had passed despite their intention to just check their feeds.

“The platforms are designed to maximize how much time we all spend on them,” he said. “It’s one thing to do that to an adult, and another thing to do it to a child, whose impulse control is still developing, whose brain is at a sensitive phase of development.”

Dr. Murthy has long indicated that he views social media as a health risk. In his May 2023 advisory on the subject, he warned that “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.”

He cautioned at the time, though, that the effects of social media were not fully understood. Research suggests that the platforms offer both risks and benefits, providing community for young people who might otherwise feel marginalized.

On Monday, he said he had concluded that “the balance of risk versus harm does not justify the use of social media for adolescents.”

“We have put young people in a position where, in order to get some benefits,” like connection with friends, “we’re telling them they have to endure significant harms,” he said. He added, “we have enough information now to act to make the platforms safer.”

Dr. Murthy has steadily dialed up his tone of urgency on the dangers of social media, comparing the current moment with landmark battles in the history of public health.

“One of the most important lessons I learned in medical school was that in an emergency, you don’t have the luxury to wait for perfect information,” he wrote in his essay on Monday. “You assess the available facts, you use your best judgment, and you act quickly.”

Sapna Maheshwari, Nico Grant and Maya C. Miller contributed reporting.