Between its outlaw image, controversial legal status and complex makeup -- the cannabis plant contains more than 400 individual chemicals -- marijuana's action in the brain and body is in many ways a mystery. The vast majority of studies on the drug have examined potential harm, as opposed to potential benefits. Even so, some medical uses are widely accepted and others are the subject of serious research. Here's a look at some potential uses of marijuana as medicine.
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In the United States, pain is the most common condition for which medical cannabis is taken. Studies show the drug is especially effective against neuropathic pain, a type of pain involving nerve damage. Marijuana is less habit-forming than opiate drugs and carries virtually no risk of a fatal overdose.
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Multiple sclerosis —
Sativex, a pharmaceutical version of cannabis, is approved in 25 countries as a treatment for painful muscle spasms arising from multiple sclerosis.
The munchies are no joke. Marijuana is sometimes prescribed to stop nausea or induce appetite in people who have trouble eating, including patients suffering from AIDS or going through chemotherapy for cancer.
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More than 100 families have moved to Colorado to access "Charlotte's Web," a cannabis strain that in some epileptic children seems to dramatically reduce seizures. Taken as an oil, the medicine is high in a chemical called CBD and low in THC, the component that makes people "high."
NFL commissioner Roger Goodell said the league is following the work of Israeli researchers who are exploring cannabis as a potential treatment for traumatic brain injury. In 2003, along with two colleagues, Nobel laureate Julius Axelrod, an American, obtained a patent on the drug for its anti-inflammatory and neuroprotective properties.
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Alzheimer's disease —
In studies of rats, marijuana helps stave off memory problems and Alzheimer's-like brain changes. A leading researcher said the drug's iffy legal status has held up further research.
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Bipolar disorder —
A small study at Harvard found that marijuana seems to stabilize the brains of people who suffer from bipolar disorder. Some studies show the drug actually raises the risk of developing mental illness, but those findings are controversial.