Opioids leave much to be desired in medical treatment. They are highly addictive, very lethal, and not all that effective for treating chronic pain. Cannabis, particularly THC, is promising for its opiate-sparing properties: preclinical work indicates that cannabis synergizes with the painkilling effects of opioids and reduces the development of tolerance (perhaps because of this synergy) but does not increase opioid-induced respiratory depression which leads to death. Moreover, states that legalize cannabis see a decrease in opioid prescriptions. A collaboration between epidemiologists at universities in the southern United States recently added to this consensus. They examined the rates of opioid overdose deaths in Colorado from 2000-2015. There was a steady increase of opioid deaths from 2000 through 2014, but after the legalizing the sale and use of cannabis, this trend appeared to reverse. The authors’ analysis suggests a decrease of 0.7 deaths in the state per month (i.e. 8-9 fewer opioid-related deaths per year) may be attributable to the legalization of cannabis in Colorado. This amounts to a 6% reduction in opioid deaths in the two years following legalization.