In 2010 , states with legalized medical marijuana recorded about 1,700 fewer deaths from prescription painkiller abuse than were expected .
While more research is needed , it is possible that the wider availability of medical marijuana for people in pain is reducing deaths by prescription opioid overdoses , researchers say .
“ Prescription drug abuse and deaths due to overdose have emerged as national public health crises , ” says Colleen L. Barry, associate professor of health policy and management at the Johns Hopkins Bloomberg School of Public Health .
“ 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 , ” says Barry , senior author of the study published online by JAMA Internal Medicine .
Using death certificate data compiled by the US Centers for Disease Control and Prevention , the researchers found that the rate of prescription painkiller overdose deaths increased in all states from 1999 to 2010 .
The yearly rate of opioid overdose deaths in states with medical marijuana laws , however , was about 25 percent lower , on average , than the rate in states without these laws .
Three states—California , Oregon , and Washington—legalized medical marijuana prior to 1999 . Ten more states adopted similar laws by 2010, the time period of the analysis . As of June 2014 , another 10 states and Washington , DC , have also passed legislation for legal use .
“ In absolute terms , states with a medical marijuana law had about 1,700 fewer opioid painkiller overdose deaths in 2010 than would be expected based on trends before the laws were passed , ” says the study’s lead author , Marcus Bachhuber of the Philadelphia Veterans Affairs Medical Center and the University of Pennsylvania .
Bachhuber cautions that the reason is unclear . It could be, he says, that people with chronic pain are choosing marijuana as an alternative treatment, or that medical marijuana laws change the way people abuse or misuse prescription pain medications, or something else entirely .
State medical marijuana laws have been passed to give access to the drug to people with chronic or severe pain , sometimes due to conditions such as cancer or multiple sclerosis. Cannabis is believed to have painkilling properties and also to relieve nausea and improve appetite .
Marijuana remains illegal under federal law, although the Justice Department has says that stopping medical use of the drug is not one of its enforcement priorities .
Brendan Saloner , assistant professor of health policy and management at Johns Hopkins and a co-author of the study , says the benefits and risks of using medical marijuana to treat chronic pain remain unclear .
“ Given the fast pace of policy change , more research is critical to understand how medical marijuana laws might be influencing both overdose deaths and the health trajectories of individuals suffering from chronic pain , ” he says .
The National Institutes of Health’s National Institute on Drug Abuse , the Center for AIDS Research at the Albert Einstein College of Medicine and Montefiore Medical Center , the Robert Wood Johnson Foundation, and the Philadelphia Veterans Affairs Medical Center supported the research .
《Medical Cannabis Laws and Opioid Analgesic Overdose Mortality in the United States, 1999-2010》, Published on Journal《The JAMA》in August , 2014 .