The studies, published on Monday in the journal JAMA Internal Medicine, compared opioid prescription patterns in states that have enacted medical cannabis laws with those that have not, reports CNN.
One study looked at opioid prescriptions between 2010 and 2015, while the other looked at opioid prescriptions between 2011 and 2016.
Opioid prescriptions also dropped by 5.88 per cent in states with medical cannabis laws compared with states without such laws, according to the studies.
"This study adds one more brick in the wall in the argument that cannabis clearly has medical applications," said David Bradford, professor of public administration and policy at the University of Georgia.
"And for pain patients in particular, our work adds to the argument that cannabis can be effective."
The new research comes as the US remains entangled in the worst opioid epidemic the world has ever seen, CNN reported.
Opioid overdose has risen dramatically over the past 15 years and has been implicated in over 500,000 deaths since 2000 -- more than the number of Americans killed in World War II.
More than 90 Americans a day die from opioid overdose currently, resulting in more than 42,000 deaths per year, according to the US Centres for Disease Control and Prevention. Opioid overdose recently overtook vehicular accidents and shooting deaths as the most common cause of accidental death in the United States, the Centre added.