As an increasing number of people have legal access to marijuana—rather, to cannabis, as it is generally referred to in medical contexts—for medical purposes, debate over these changes in the law continues. Medical experts and ethicists continue to discuss what good it might do, what harm it might do, and whether the good outweighs the harm. Some of this debate is misinformed, on both sides, but it is necessary, as with any treatment, to balance the potential benefits with an awareness of the possible downside.
Though the long-term effects of cannabis are not well studied, some fears about cannabis are misplaced. Though there are people who make a habit of using marijuana, cannabis is not habit-forming on a chemical level the way some painkillers are. In fact, a recent study found that in states that have legalized cannabis for medical purposes, deaths from opioid painkillers, which can be addictive, are 25 percent lower than in states that have not. Although only 60 percent of deaths from these medications are in people with prescriptions, prescribing cannabis instead can lead to an overall reduction in the amount of these drugs in circulation.
Cannabis has a long history as a medical treatment. More than 3,000 years ago, cannabis was used to alleviate headaches, prevent nausea, treat gastrointestinal disorders, relieve constipation, ease labor pains, and stop nosebleeds. The substances tetrahydrocannabinol and cannabidol have properties that are medically useful in certain situations. and in 1990 researchers found sites in the body that specifically respond to these substances. Now it is used to treat stomach cramps, to help chemotherapy patients deal with nausea, to help people who have conditions or are undergoing treatments that affect the appetite avoid malnourishment, and to treat muscle spasticity, and research is ongoing into other possible benefits.
For example, recent studies suggest marijuana may have some use in treating epilepsy. Patients with severe forms of the seizure disorder have shown significant reductions in symptoms—in particular, a greatly reduced frequency of seizures—from using cannabis. The reduction seems to be primarily due to cannabidiol rather than the psychoactive component, THC, though both substances have anti-convulsant effects.