Fourteen states have legalized marijuana for medical uses and the Department of Justice has announced it will not prosecute people who use marijuana while under a doctor’s care and in accordance with state rules.
But even as the regulatory landscape clears, the medical issues associated with smoked marijuana remain muddled. Scientists simply don’t know how effective it is as a therapeutic agent. Remarkably, the literature contains fewer than 20 randomized trials of smoked marijuana for all therapeutic indications combined.
Among these, research findings that support using marijuana for neuropathic pain are probably the strongest. For example, in a trial of AIDS patients published in Neurology, scientists found that 52% of those who smoked marijuana reported at least a 30% reduction in pain, as compared with 24% of those who smoked placebo cigarettes.
Smoked marijuana has also been shown to have a modest anti-nausea effect in cancer patients receiving chemotherapy, and to improve appetite and trigger weight gain in HIV-positive patients.
That said, marijuana has not been shown to help patients with a variety of other conditions ranging from epilepsy to immune system disease.
The muddled situation is further complicated by the fact that the FDA doesn’t regulate marijuana. That means, among other things, that the potency of products available in medical-marijuana dispensaries is likely to vary.
“It’s difficult to understand how we can call it medicine if we don’t know what’s in it,” Stephen DeAngelo told the Wall Street Journal. DeAngelo runs a medical-marijuana dispensary in Oakland.
Marijuana, it must be noted, has been associated with palpitations, memory loss, anxiety, psychotic experiences and, yes, an inability to concentrate.
It also carries a risk of physical dependence, though it is not as addictive as nicotine or alcohol. Smoked marijuana may also irritate bronchial tissue, but a study in Cancer Epidemiology, Biomarkers & Prevention found no link between smoking marijuana and lung cancer.