A warning issued by the United States surgeon general, Dr. Vivek Murthy, on Tuesday provided guidance about an issue that has been front of mind for American parents for years: the negative effects of social media on the mental health of young people.

These types of public health advisories are infrequent, but sometimes become turning points in American life.

Cigarettes

It took a surgeon general’s report in 1964 and decades of effort that followed to change the perception of smoking in America from a glamorous habit to one with deadly consequences.

The annual per capita cigarette consumption in the United States had increased from 54 cigarettes in 1900 to more than 4,000 cigarettes in 1963 when the first research suggested links between smoking and cancer.

That prompted Dr. Luther L. Terry, the surgeon general under Presidents John F. Kennedy and Lyndon B. Johnson, to issue a landmark report on the health hazards and consequences of smoking in 1964.

Dr. Terry described the crisis as a “national concern.”

The fallout was swift. In 1965, Congress required all cigarette packages distributed in the United States to carry a health warning. In 1970, cigarette advertising on television and radio was banned.

Tobacco has continued to be a target of surgeons general, who in later years highlighted concerns about secondhand smoke and tobacco promotions that targeted children. And in 2016, Dr. Murthy published a comprehensive report that called e-cigarettes and tobacco vaping “a major health concern.”

AIDS

Dr. C. Everett Koop, the surgeon general under President Reagan, was credited with changing the public discourse around the H.I.V./AIDS epidemic during the 1980s. In 1986, he issued a generation-defining report on AIDS. In plain language, the report discussed risk factors and ways that people could protect themselves, including the use of condoms for safer sex.

But frank discussion of sexual topics later tripped up a surgeon general who served under President Bill Clinton, Dr. Joycelyn Elders. Although her efforts to expand access to health screenings and sex education were praised by some, she resigned under pressure in 1994 after she proposed the distribution of contraceptives in schools and condoned teaching children about masturbation as a way to prevent the transmission of H.I.V., among other views that drew the ire of conservatives.

Violence on TV and in video games

In 1972, Dr. Jesse L. Steinfeld, the surgeon general under President Richard Nixon, called for “appropriate and immediate remedial action” after a report found a “uniformly adverse effect” on children who watch televised violence.

Drunken driving

In the late 1980s, the numbers were startling: About 25,000 people in the United States died in drinking-related traffic accidents annually.

In one of his last acts as surgeon general, Dr. Koop called for tough new blood-alcohol level standards for drivers in 1989, as well as an increase in taxes on alcoholic beverages and a restriction of advertising of alcoholic beverages. He also called for the elimination of happy hours and the immediate suspension of any licensed driver found to be above the legal limit.

Obesity

By the turn of this century, some 300,000 Americans were dying from illness caused or worsened by obesity, prompting Dr. David Satcher, a surgeon general under President Clinton, in 2001 to call for major steps to act on what he described as an epidemic.

But the crisis has only grown. From 1999 through 2017, the prevalence of obesity in the U.S. increased to 42 percent from 30 percent, and severe obesity increased to 9 percent from 5 percent, according to the C.D.C.

Gun violence and loneliness

Social media is not the only concern of the current surgeon general. Dr. Murthy has also called gun violence in America a public health issue and more recently an epidemic.

He has called for more research and government intervention. Former surgeons general and researchers have also called for a policy change centered around treating gun violence as a public health crisis. Nearly 50,000 Americans died from gun-related injuries in 2021, more than in any other year on record, according to the C.D.C.. It is the leading cause of death among children in the United States.

And earlier this month, Dr. Murthy issued a surgeon general advisory and new framework to address “the public health crisis of loneliness, isolation, and the lack of connection in our country.” This trend was magnified by the coronavirus pandemic, he said.

The physical health consequences of poor or insufficient connection include higher risks of other health ailments.

Here’s his advice on how to feel less lonely.

Notably, the report on loneliness does not recommend social media as a form of connection, and urges Americans to ensure digital interactions do not “detract from meaningful and healing connection.”