PainRelief.com Interview with:
Roger Chou, MD
Professor of Medical Informatics and Clinical Epidemiology, School of Medicine
Professor of Medicine, School of Medicine
2012-present Director, Pacific Northwest Evidence-based Practice Center
Medical Informatics and Clinical Epidemiology, School of Medicine
Oregon Health & Science University
Portland, Oregon

PainRelief.com: What is the background for this study?

Response: We started this review five years ago, it was funded by the Agency for Healthcare Research and Quality (part of the Department of Health and Human Services). Because there is a lot of interest in use of cannabis products for pain and because new research is coming out, we planned to do it as a “living” review, which means that instead of reviewing all the studies at one point of time and publishing the findings and then being done, we continually searched for new studies and updated our analyses as they became available. We conducted this review over 5 years and this article reports the final findings of the review.

An important thing to know is that cannabis products are complicated because cannabis contains different chemicals that are thought to have different properties, the most important being THC and CBD.  THC is considered the psychoactive component and CBD isn’t thought to have psychoactive properties but may have medical or therapeutic properties.  Different cannabis products (as well as the plants themselves) vary in how much THC or CBD is contained, ranging from “pure” THC or CBD to mixed products.  We separated cannabis products into different categories based on the amount of THC relative to CBD, which is important because the benefits or harms may vary according to how much THC or CBD is present.  We also looked at whether the products were taken from the plant or made in a lab (synthetic) as well as how the products were taken (e.g., a capsule or cream/oil or spray etc) which can all impact how the products work.

Last Updated on January 8, 2026 by PainRelief.com