Researchers have found that people suffering from chronic foot pain as a result of the AIDS virus gained relief from smoking marijuana.
The study by researchers at the General Clinical Research Center at San Francisco General Hospital Medical Center, looked at 50 HIV patients with HIV-associated sensory neuropathy, a painful and often debilitating condition that is the most common peripheral nerve disorder that occurs as a complication of HIV infection.
Severe peripheral neuropathy usually occurs in the feet and is characterized by tingling, numbness, the sensation of pins and needles, burning, and sharp intense pain, severe which can make walking or standing difficult.
It affects about a third of HIV-infected people.
The mainly male participants in the study, apart from the nerve pain were in stable health and had all been marijuana smokers but not drug abusers and were told to stop using it prior to the study.
Half of the group smoked marijuana cigarettes three times a day for five days, while the other half smoked placebo cigarettes that were identical other than having had the cannabinoids, the primary active components of the plant, extracted.
The patients smoked the cigarettes under supervision as inpatients at the hospital medical center.
The patients smoking cannabis experienced a 34 percent reduction in intense foot pain, twice the rate experienced by patients who smoked the placebo and the volunteers had no serious side effects.
Lead researcher Dr. Donald I. Abrams, a professor of clinical medicine at UCSF, say the results provide evidence that there is a measurable medical benefit to smoking marijuana for these patients.
Abrams who was one of the first doctors to study the AIDS virus at the start of the epidemic, says he hopes his findings will provide evidence that marijuana is medicine.
Marijuana remains an illegal drug under U.S. federal law, even though many experts believe it should be legalised for medical uses such as treating pain or nausea in AIDS or cancer patients; the issue has created fierce debate.
However David Murray, the chief scientist for the White House Office of National Drug Control, has voiced skepticism over the study and suggested it is misleading.
This is despite the fact that the study found the relief from smoking marijuana was comparable to that provided by pills now used to treat such nerve pain.
But not all patients are helped by the anti-seizure medications used and many cannot tolerate them and suffer unpleasant side effects.
For many marijuana offers an alternative which improves their quality of life.
The study is the first of several clinical trials of medicinal cannabis to be completed under the auspices of the University of California's Center for Medicinal Cannabis Research.
Co-author Dr. Cheryl A. Jay, a UCSF professor of clinical neurology, says even though antiretroviral treatments have reduced the prevalence and severity of many HIV-related neurological complications, one of every three patients is still affected by severe nerve pain.
Dr. Jay says as there are no FDA-approved treatments for HIV-related neuropathy, the study suggests new avenues to manage such neuropathic pain.
The study is published in the journal Neurology.