How much evidence exists to support for medical cannabis as a treatment for various conditions?

Rubin R. Medical marijuana is legal in most states but physicians have little evidence to guide them. JAMA 2017;317(16):1611-1613 Abstract

Why was this study conducted?

Physicians lack basic knowledge about cannabis because they never learned about it in medical school. Furthermore, because it is not a federally-approved treatment (in either the U.S. or Canada) backed by randomized controlled trials, there is no authorized source of information on dosage, indications and contraindications. Using interviews, this report summarizes some of the challenges faced by physicians when deciding whether, or how, to recommend medical cannabis to their patients.

What does this study add?

According to a leading oncologist in California who uses medical cannabis in his practice, some of the best evidence for the effectiveness of medical cannabis is for the management of symptoms related to cancer and its treatment. However, even this physician admits that many questions remain and evidence for many of the other claims for medical cannabis is insufficient. Some medical schools in the U.S. are starting to develop courses on medical cannabis and continuing education courses are offered in several states (in some states, physicians must complete a set number of hours of education before he/she can become a registered prescriber). Because so many physicians are reluctant to recommend medical cannabis, clinics and websites have popped up that claim to offer “easy” access. It can be argued that such websites and clinics violate the guideline that a physician should have an established relationship with a patient before recommending medical cannabis.

Is there anything else I should know?

In addition to looking at the literature, the author interviewed physicians who have been involved in the medical cannabis controversy, including an internist in Florida, oncologist in California and emergency department physician in Vermont. The views expressed are personal and may not reflect those of most physicians in the U.S. or elsewhere.