The study, from the University of California at San Francisco, found smoked marijuana to be effective at relieving the extreme pain of a debilitating condition known as peripheral neuropathy. It was a study of HIV patients, but a similar type of pain caused by damage to nerves afflicts people with many other illnesses including diabetes and multiple sclerosis. Neuropathic pain is notoriously resistant to treatment with conventional pain drugs. Even powerful and addictive narcotics like morphine and OxyContin often provide little relief. This study leaves no doubt that marijuana can safely ease this type of pain.