"Eighty five percent of the BPG [Berkeley Patients Group] sample reported that cannabis has much less adverse side effects than their prescription medications. Additionally, the top two reasons listed by participants as reasons for substituting cannabis for one of the substances previously mentioned were less adverse side effects from cannabis (65%) and better symptom management from cannabis (57.4%).

"Conclusion
"The substitution of one psychoactive substance for another with the goal of reducing negative outcomes can be included within the framework of harm reduction. Medical cannabis patients have been engaging in substitution by using cannabis as an alternative to alcohol, prescription and illicit drugs."