There's a body of research showing that painkiller abuse and overdose are lower in states with medical marijuana laws.
/www.washingtonpost.com/news/wonk/wp/2016/07/13/one-striking-chart-shows-why-pharma-companies-are-fighting-legal-marijuana/?hpid=hp_hp-more-top-stories-2_wb-pharmapot%3Ahomepage%2Fstoryin the 17 states with a medical-marijuana law in place by 2013, prescriptions for painkillers and other classes of drugs fell sharply compared with states that did not have a medical-marijuana law.
In medical-marijuana states, the average doctor prescribed 265 fewer doses of antidepressants each year, 486 fewer doses of seizure medication, 541 fewer anti-nausea doses and 562 fewer doses of anti-anxiety medication.
But most strikingly, the typical physician in a medical-marijuana state prescribed 1,826 fewer doses of painkillers in a given year.