Millions of people in the U.S. with opioid use disorder also use other illicit substances such as methamphetamine or cocaine, The New York Times reports.

The increase in polysubstance use is making treatment more difficult, experts say. Treatments for opioid use disorder counteract the worst effects of fentanyl and heroin. But there are no approved medications to treat addiction to meth or cocaine. Meth can also reduce the effectiveness of opioid use disorder treatments.

Over the past three years, studies of people with opioid use disorder have consistently shown that 70% to 80% also use other illicit substances. “It’s no longer an opioid epidemic,” said Dr. Cara Poland, an associate professor at the Michigan State University College of Human Medicine. “This is an addiction crisis.”

The Biden administration has been spending billions of dollars for opioid interventions and policing traffickers, but has not focused much attention on meth and cocaine, according to the article. According to provisional federal data, more than 34,000 deaths were attributed to meth and 28,000 to cocaine in the 12-month period ending in May 2023.