An end to the prohibition of medical marijuana in the US might prevent tens of thousands of deaths every year from prescription drug overdoses, new research suggests.

In states that have decriminalized medical weed, an average of 25 percent fewer people are dying from overdoses of opioid analgesics each year compared to the nation as a whole, according to a scientific paper published in JAMA Internal Medicine. That is 1,729 less deaths than expected for every state that had legalized medical marijuana in 2010, the study's final year.

Meanwhile, traditional control strategies such as government monitoring programs and making patient access to prescription drugs more difficult simply aren't working, the research indicates.

So far 23 states have legalized medical medical use, but not all were included in the study, as only 13 of them had scrapped prohibition by the end of the 11-year research period.

"Twenty-five percent is an enormous difference," Alli Kraus, a harm reduction expert, told VICE News.

Nationwide, prescription drug overdose abuse and deaths have been steadily increasing, now accounting for more accidental deaths than car crashes, according to Amanda Reiman of the Drug Policy Alliance. The issue prompted the White House to prioritize prescription drugs in its 2014 drug control strategy.

"Prescription drug overdose is the number one cause of accidental death in the US," Reiman said. "We're talking about a huge issue that's getting worse. Even though we can't prove a causal link, given that prescription drugs are such a problem, it's a very important thing to look at."

The study didn't offer a conclusion as to why states that have legalized medical marijuana are seeing fewer overdose deaths. But the findings are significant enough to show that the correlation is definitely worth more academic interest, Kraus said. "It's worth investigating the cause."

The researchers did suggest possible reasons for fewer drug deaths where medical marijuana is legal.

"As our awareness of the addiction and overdose risks associated with use of opioid painkillers such as Oxycontin and Vicodin grows, individuals with chronic pain and their medical providers may be opting to treat pain entirely or in part with medical marijuana, in states where this is legal," said Dr. Colleen Barry, the lead author of the study.

The research appears to corroborate what marijuana policy advocates and harm reduction experts have long argued using anecdotal evidence: that marijuana can offer a less deadly alternative to prescription drugs, according to Reiman.

"This is something that medical marijuana patients have been doing for years," she said. "This isn't a new thing to think, it confirms something that we've seen from multiple research studies."

The research included overdoses of all kinds, and didn't determine whether the victims legally obtained drugs resulting in death. Buying drugs illegally is a more risky proposition than over the counter, because users have few ways of determining what exactly they are buying.

Although most drug deaths are a result of pill overdoses, thousands are caused by other opiates such as heroin. In many cases, alcohol is a factor as well — and unlike cannabis, booze can have deadly consequences when combined with opiates, according to Kraus.

One of the reasons prescription drugs like painkillers can be deadly is that users build up a tolerance, requiring higher doses. Marijuana isn't likely to kill users, and in fact often helps those addicted to opioid analgesics to kick the habit, the study suggests.

The findings are enough to warrant further research, experts say, especially considering that states with more liberal drug policies — including access to medical marijuana — may have more mechanisms, such as police carrying the common overdose suppressant Naloxone, to respond to potentially fatal incidents.

"The results could be a function of other medical therapy people are getting as well," Kraus said. "It's worth getting more context."

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