Smoking marijuana helps relieve the aching, burning nerve pain associated with HIV, a clinical trial suggests.

People who smoked marijuana reduced their daily nerve pain by 34 per cent, compared with 17 per cent in a placebo group, researchers report in Tuesday's issue of the journal Neurology.

Dr. Donald Abrams and his team of researchers from San Francisco General Hospital in California randomly assigned 50 people with HIV-associated sensory neuropathy, the most common HIV nerve disorder, to either smoke marijuana or to smoke a placebo cigarette.

Participants smoked the joints or cigarettes three times a day for five days during the study, which ran from 2003 to 2005. All of the subjects had previously smoked marijuana, but they were not considered drug abusers, and they were told to stop before the study began.

None of the volunteers displayed serious side-effects.

"Smoking marijuana was well tolerated and effectively relieved chronic nerve pain from HIV-associated sensory neuropathy," said Abrams.

"Our findings show the amount of relief from smoking marijuana is comparable to relief provided by oral drugs currently used for chronic nerve pain."

Disabling complication

HIV-associated sensory neuropathy is a nerve pain that affects about one-third of those infected with HIV. It usually occurs in the feet, and can include tingling, numbness, the sensation of pins and needles, burning, or sharp, intense pain. When severe, the pain may make it difficult to stand or walk.  

Currently, people with HIV and chronic nerve pain commonly take anticonvulsant drugs to ease pain, but some don't respond to the medication or cannot tolerate it, leading to an interest in alternatives.

"The results of this first study indicate that cannabis may indeed be useful in the amelioration of a very distressing, disabling, and difficult to treat complication of HIV," said Dr. Igor Grant, a professor of psychiatry at the University of California San Diego School of Medicine.

However, David Murray, the chief scientist at the White House Office of National Drug Control Policy, said the study was "not terribly convincing," because of methodological problems, such as the small sample size.

"People who smoke marijuana are subject to bacterial infections in the lungs," said Murray. "Is this really what a physician who is treating someone with a compromised immune system wants to prescribe?"

Dr. Mark Ware, a researcher at McGill University in Montreal who is conducting similar experiments, defended the statistical reliability of Abrams's study. 

Abrams's study is one of the first recent clinical trials of medical marijuana to be done in the U.S., where use of the drug is debated fiercely.

Canadians have been able to apply for a licence to grow and smoke medicinal marijuana since 2001.

With files from the Associated Press