Though small, the study adds to a growing body of evidence suggesting that cannabis has painkilling properties that may be useful in medicine, perhaps in addition to other treatments. THC extracts have been shown to help ease cancer pain and the nausea associated with chemotherapy, while a few small
studies in hospital populations have found that smoked marijuana can help relieve neuropathic pain.
But medical marijuana isn’t ready to become a mainstream chronic pain treatment, says Andrew McDavid, MD, director of the division of pain management at Scott & White Healthcare, in Temple, Texas.
“The studies out there show some decrease in pain, but it’s not alarmingly or shockingly great,” says Dr. McDavid, who was not involved in the new research. “Although it may have some use, it’s probably going to need to be used with something else, if it’s approved.”
As the study notes, the pain relief the patients experienced from marijuana was modest compared to that seen in studies of analgesic medications such as gabapentin (Neurontin) and pregabalin (Lyrica).
Christopher Gharibo, MD, an anesthesiologist at the New York University Hospital for Joint Diseases, in New York City, points out that the study didn’t address whether marijuana enabled the patients to perform everyday activities without pain—the best test of a chronic pain treatment.
“I’m not convinced [marijuana] helps from a functional standpoint,” he says. “I’m not even impressed by the pain reduction. We have analgesics that do much better.”
The potential long-term side effects of habitual marijuana use could prove problematic as well, Dr. Gharibo adds. Over time some patients may experience weight gain, a generalized feeling of sedation, and even changes in mood and cognitive function, he says.
The study participants did report some minor side effects, including coughing, dizziness, headache, and dry eyes. Few reported feeling “high” or euphoric, however, which suggests that abuse or addiction is not a major concern with amounts as small as those used in the study.
“We had a total of three single episodes where patients felt a little bit high,” Ware says. “So it was extremely rare. The possibility that one would become addicted is low.”
Still, if marijuana were to become a more common pain treatment, it’s possible that some patients might overdo it, Dr. McDavid says. “We saw the problem with narcotics. You can’t ever predict which people, when prescribed, will abuse it or not. Obviously there needs to be more research.”
