New research conducted by Columbia University’s Mailman School for Public Health suggests that the availability of medical marijuana may reduce the use of opioid drugs. The study concluded that fewer people were killed in car accidents who tested positive for opioids (even prescription opioids) in states where there was access to medical marijuana than when before laws were passed in each state legalizing its use.
The researchers pored over the 1999-2013 Fatality Analysis Reporting System data from 18 states within the US. They observed data of 80% drivers who fatally crashed their cars during that time period and whether or not they tested positive for opioids at the time of their death and contrasted the data of opioid toxicology of fatal car accidents before and after medical marijuana laws went into effect.
There was a positive correlation with lawful medical marijuana and reduced opioid use.
The positive correlation with medical marijuana and reduced opioid use was, however, only observed in the 21-40 age set. Researchers do not believe that the legalization of medical marijuana will contribute to lowered opioid use in those over the age of 45, specifically because most marijuana users are in their 20’s and 30’s.
Senior author of the study Guohua Li, MD, DrPH, a Mailman School professor of Epidemiology, and founding director of the Center for Injury Epidemiology and Prevention at Columbia stated:
“This study is about the possible substitution relationship between marijuana and opioids. The toxicological testing data for fatally injured drivers lend some suggestive evidence that supports the substitution hypothesis in young adults, but not in older adults.” 
This new study could help states curb the current opioid crisis in the United States. Since 1999, the opioid prescriptions have tripled within the country. In 2014 alone, 14,000 people died from opioid overdoses, which is around 40 people per day. And while many states have tightened their laws on obtaining opioids, many fear that this will create more people turning to illegal drugs in order to satisfy their cravings.
Recently, the Drug Enforcement Administration (DEA) has cracked down on kratom, an herbal supplement that many have used to treat their chronic pain in an alternative manner.
The tightened opioid laws do not necessarily equate to more lax rules on medical or recreational marijuana, which some fear could create a problem.
At the moment, 22 states have passed medical marijuana laws, with California pioneering efforts in 1996 as the first state to do so.
Study authors note that more research will be needed to determine whether or not legalizing marijuana will have a long term impact on the country’s opioid epidemic.
 Huffington Post