WITH THE publication Thursday of a comprehensive 428-page report on drug and alcohol misuse, Surgeon General Vivek H. Murthy has added his voice to those calling for a more vigorous, better informed approach to addiction in the United States. Dr. Murthy emphasizes the need for a public-health-based approach to the problem, one that offers sufferers less moralizing and more medically based treatment options; fortunately, that seems already to be the emerging consensus, one of the few things Republicans and Democrats agree on. Backed by the authority of Dr. Murthy’s office, the document is likely to become a standard reference; a 1964 report on smoking and health by an earlier surgeon general, Dr. Luther Terry, became a cultural milestone.

As the report makes clear, the growth in the United States’ drug problem comes from opioids, fed both by misuse and diversion of legal, prescribed drugs and by heroin. In fact, the report’s statistics on alcohol, cocaine and hallucinogen consumption show no significant change between 2002 and 2014. Meanwhile, deaths from prescription-opioid and heroin overdoses have surged. The report also documents a measurable recent uptick in marijuana use, probably linked to its recent legalization in several states. The surgeon general identifies several non-trivial public health risks of rising marijuana usage; advocates of legalization may find themselves challenged to explain, better than they have so far, how those risks can be mitigated.

But the opioid crisis is the greater danger by far. President-elect Donald Trump lamented it time and again as he toured the Rust Belt and Appalachian regions where the ravages of these drugs are particularly severe. In a speech on the subject last month, he demagogically linked drug addiction to the “sanctuary cities” movement, claiming participating towns “refuse to turn over illegal immigrant drug traffickers for deportation.” Much of what he proposed, however, was at least plausible, indeed mainstream, including alternatives to jail for users and greater access to treatment. He advocated tighter regulation of prescription opioid production in the United States, as well as less regulation of medications designed to treat addiction. He called for a crackdown on shipments of synthetic opioids through the U.S. postal system from China.

Keeping his promise to repeal Obamacare, however, would mean nullifying a law that dramatically expanded access to drug and alcohol treatment, and provided funding, through Medicaid, for low-income people. This potential contradiction is just one of many reasons to be concerned about the GOP’s plans for health care in the Trump years.