The unavoidable tension in attacking the opioid crisis is which time frame you’re talking about.

In the short term, many policies that would limit opioid prescriptions for the purpose of saving lives would cause people to turn to heroin or fentanyl.

In fact, over a 5-to-10-year period, that would increase deaths, not decrease them, according to a simulation study published in the American Journal of Public Health. The study was conducted by three Stanford University researchers, Allison Pitt, Keith Humphreys and Margaret Brandeau.

“This doesn’t mean these policies should not be considered,” said Mr. Humphreys, a former senior policy adviser at the White House Office of National Drug Control Policy during the Obama administration. “Over longer periods, they will reduce deaths by reducing the number of people who initiate prescription opioids.”

A large proportion — 80 percent by one estimate — of heroin users in the United States previously used prescription opioids. In some cases, they were directly prescribed narcotic pain relievers, perhaps after a painful dental procedure or operation. In addition, drugs prescribed to one person can be diverted to others who don’t use them for medical purposes. So restricting opioid prescriptions would seem to make sense.