The turning point in America's drug overdose (OD) crisis came in August 2023, a new study says.

That's the month when the national drug OD death rate began to decline, researchers reported June 12 in JAMA Network Open.

OD death rates are now in a sustained slow down after two decades of increase, researchers said.

"This is an unprecedented shift in the modern drug crisis," lead researcher Lori Post, director of the Buehler Center for Health Policy and Economics at Northwestern University Feinberg School of Medicine, said in a news release.

However, the U.S. isn't out of the woods yet, Post warned. The current OD death rate remains higher than any time dating back to the mid-1800s.

"Even with this promising decline, drug overdose death rates remain near historic highs," Post said. "Things are better but still not good."

For the study, researchers tracked the 800,645 drug overdose deaths that occurred between January 2015 and October 2024.

Results show the national OD death rate increased from 14.5 deaths per 100,000 Americans in 2015 to 33.2 deaths per 100,000 in August 2023.

At that point, the monthly OD death rate began declining at an accelerating pace, coming down to 24.3 deaths per 100,000 as of October 2024.

The study didn't examine what caused this inflection point, but Post suspects efforts to stem illicit drug supplies probably turned the tide.

"The supply side likely explains much of the downturn — pointing to upstream drivers like shifts in the drug supply rather than downstream fixes such as harm-reduction strategies and treatment," Post said.

For example, changes in the availability or potency of illicit opioids might be one explanation, given that opioid OD death rates have decelerated more rapidly than the death rates associated with stimulant overdoses, the study says.

More research is needed to figure out the exact causes of the turnaround, Post said.

"Without identifying what worked, we risk losing ground," she said.

The data show that the Midwest was the nation's first region to make headway, with its OD deaths starting to slow in 2022 — a full year earlier than the national average. The shift largely went unnoticed at the time.

On the other hand, the West's OD death rate didn't start slowing until 2024, marking a two-year lag between regions.

"Different regions mean different outbreaks and recovery time periods," Post said. "These differences are not simply disparities in outcomes; rather, they reflect distinct epidemic timelines."

She noted that the West "caught fentanyl" later than other regions, with widespread exposure not occurring until 2019-2020.

"They were the last to catch fentanyl, so the last to recover," Post said.

This is the first study to identify sustained declines in drug OD deaths versus temporary plateaus, she noted.

Brief plateaus occurred in 2018-2019 and 2022-2023, but the data show these were temporary pauses and not true turning points, according to the study. Drug OD deaths truly began to steadily decline beginning in August 2023.