Medical marijuana legalization led to a 6% drop in opioid prescriptions to Medicaid patients. Adult-use legalization led to an additional 6% decrease.
Cannabis can relieve chronic pain in adults, so advocates for liberalizing marijuana laws have proposed it as a lower-risk alternative to opioids. But some research suggests cannabis may encourage opioid use, and so might make the epidemic worse.
The new studies don’t directly assess the effect of legalizing marijuana on opioid addiction and overdose deaths. Instead, they find evidence that legalization may reduce the prescribing of opioids. Over-prescribing is considered a key factor in the opioid epidemic.
Both studies were released Monday by the journal JAMA Internal Medicine.
A growing body of evidence suggests that cannabinoids — chemical components in Cannabis plants or certain synthetic compounds — can be effective in alleviating pain, either alongside or in place of opioids.
As medical marijuana becomes more accessible in the U.S., it could serve as a safer option for some kinds of pain relief and could even help to reduce the number of people addicted to opioids, experts told Live Science.
When a person uses marijuana, cannabinoids in the drug bind to cannabinoid receptors in the human body. These receptors are part of an existing pain-mitigation network that produces endocannabinoids — “our own opiates” — and primes the body to be receptive to compounds with a similar chemical makeup, Dr. Donald Abrams, a professor of medicine at the University of California, San Francisco, told Live Science.
“We have this whole system of receptors and endogenous [internal] cannabinoids that are probably present to help us modulate the sensation of pain,” Abrams said. “That makes it sort of obvious that other cannabinoids — those that come from plants — could also have some benefit for pain.”
THC, or tetrahydrocannabinol, is the cannabinoid in marijuana that is chiefly responsible for the drug’s psychoactive effects, and cannabidiol, or CBD, is another active cannabinoid that does not cause feelings of intoxication.
Evidence from clinical studies suggests that cannabis or cannabinoids are effective in mitigating chronic pain, neuropathic pain (pain caused by a disease or injury affecting the nervous system), and involuntary and continuous muscle contractions associated with multiple sclerosis, Dr. Kevin Hill, an associate professor of psychiatry at Harvard Medical School, told Live Science in an email.
In a study published in September 2015 in the journal JAMA, Hill reviewed 74 medical studies on marijuana use for pain relief dating from 1948 to 2015. He found that there were positive results across 24 trials for patients with chronic pain, neuropathic pain and multiple sclerosis.