Heroin has surpassed prescription painkillers as the leading cause of death from drug overdose, according to the Centers for Disease Control and Prevention.

The latest numbers account for the 25,426 deaths by overdose that took place between 2012 and 2014.

As recently as 2010, heroin ranked fifth, making up nearly 8% of overdose deaths compared with 14% from oxycodone. By 2014, heroin-related deaths tripled to 23%.

That shift is largely the result of addicts buying heroin, which became cheaper as more of it was imported into the U.S. At the same time, clinicians began writing fewer prescriptions and more closely monitoring those who might have problems, making it harder for addicted patients to get controlled substances.

Dr. Stuart Gitlow, immediate past president of the Board of Directors for the American Society of Addiction Medicine, said the decrease in opioid prescribing should have been followed by an immediate increase in the availability of medication-assisted treatments like buprenorphine.

“Ultimately, we took too long to increase availability of treatment,” Gitlow said. The rate of heroin use in the U.S. is now at its highest levels in two decades, according to the findings of the United Nation's World Drug Report released in June.

Gitlow hopes the latest figures from the CDC will encourage policy makers and industry stakeholders such as insurers to make treatment more readily available. Health insurance trade groups and provider groups have debated whether medication-assisted treatment should be a mandated benefit under the Affordable Care Act's essential benefits provision.

“People need to realize addictive disease is about addiction not about a drug,” Gitlow said.

Public health officials saw legislation passed this summer that encouraged and funded treatment as a way of decriminalizing addiction. The changing demographic of the epidemic, which has spread from the inner city to rural America in large part because of over-prescribing, has also affected the profile of the addict.

The recent increase seen in the use of illegal drugs raises concerns that the focus could once again shift away from addressing addiction as a public health issue in favor of going back a law enforcement approach.

“From a medical standpoint there is no difference between heroin and prescription morphine; the drugs do the same thing,” Gitlow said. “So we see no reason why one should be treated differently from another.”