Marijuana helps relieve chronic pain, study finds

Pain relief by marijuana was modest as the most potent dose only brought down average daily pain scores by 0.7 points on an 11-point scale, said the researchers.

Mark A. Ware of McGill University in Montreal, Canada and colleagues also found that smoking weed with 9.4 percent of the active ingredient tetrahydrocannabinol (THC) helped the study participants sleep better, and cut down the signs of depression and anxiety.

Results of the study are in line with previous trials that have suggested marijuana as a potential pain reliever, but with some limitations. Lead author Dr. Mark Ware, a neuroscientist, describes marijuana as “another potential tool” for treating chronic pain.

“It's been known anecdotally,” researcher Mark Ware, MD, assistant professor of anesthesia and family medicine at McGill University in Montreal, told WebMD. “About 10% to 15% of patients attending a chronic pain clinic use cannabis as part of their pain [control] strategy.”

Study details
The researchers evaluated 21 men and women, who were suffering from chronic nerve pain (also called neuropathic pain). Average age of the patients was 45 years.

The patients were administered with three different potencies of marijuana: with 9.4 percent tetrahydrocannabinol (THC) content, 6 percent THC and the least potent does of 2.5 percent THC.

“Each person was in the study for two months, and used all four strengths [including placebo],” said Ware. Thrice a day, for five days, participants were given a 25 milligram hit of one of four treatments, without any knowledge of which strength they were using.

A nine day break was given between each treatment.

Patients smoking the highest concentration of THC marijuana (9.4 percent) reported lower pain scores than when smoking the placebo. On a scale of 10, the highest strength of THC brought down the pain to 5.4, while the placebo brought it down to 6.1.

“We've shown again that cannabis is analgesic,” Ware says. “Clearly, it has medical value.”

Calling the cannabinoid family, which includes marijuana, to be an “emerging as an interesting new class of drugs for pain management,” Ware noted that patients of chronic pain will always need more than just drugs.

According to him, it works by “changing the way the nerves function.”

Side effects cannot be ignored
Dry eyes, headache, numbness, cough, and a burning sensation in the pain area were the reported side effects.

Calling the cannabinoid family, which includes marijuana, to be an “emerging as an interesting new class of drugs for pain management,” Ware noted that patients of chronic pain will always need more than just drugs. He advised accompanying behavioral and physical therapy.

Support for medical marijuana?
The recent hype about the legal use of medical marijuana has been questioned and countered by some. The study would calm the debate as it proves the drug can actually help those in pain, but researchers have suggested that more research is required before the drug can be prescribed.

“If medical cannabis is not available where a patient lives, then obtaining it will take the patient outside of the law, often for the first time in his or her life,” wrote Henry J. McQuay of Oxford University in an accompanying editorial. “Good evidence would at least buttress that decision.”