Does marijuana help chronic pain or post-traumatic stress disorder (PTSD)? Two reviews funded by the VA system found a lack of evidence that plant-based cannabis helps either condition. Researchers reviewed 27 chronic pain trials. They found low-strength evidence that cannabis helps neuropathic pain, but insufficient evidence that it is effective in other pain populations. Harms include increased risk for motor vehicle accidents, psychotic symptoms, and short-term cognitive impairment. (Ann Intern Med 2017;167:319-331)

There were no randomized trials for PTSD, but there were two systematic reviews and three observational trials. None of the studies found benefit of cannabis for PTSD. The authors noted that there are ongoing randomized trials and six other studies expected to be completed in three years regarding cannabis and PTSD. Nevertheless, there is insufficient evidence today to draw conclusions about the benefits and harms of plant-based cannabis preparations in patients with PTSD. (Ann Intern Med 2017;167:332-340)