Is Marijuana Medicine? Questions Remain


Despite a federal ban, little research into its effectiveness, and lack of approval by the U.S. Food and Drug Administration (FDA), the use of marijuana for medical purposes has been approved in 23 states and the District of Columbia as of August 2014. More are likely to follow.

In Massachusetts, citizens overwhelmingly approved a ballot question in 2012 permitting marijuana use by patients with ‘debilitating medical conditions.’ With 63% of voters saying yes to the initiative, marijuana was declared medicine by plebiscite, a departure from the nation’s traditional way of testing and approving medications through controlled scientific clinical trials and subsequent FDA review and approval.

With regulations in place for the state’s medical-marijuana program that commenced in January 2013, and as marijuana dispensaries prepare to open, here’s a snapshot of the existing evidence on marijuana as medicine and what we believe patients should think about if they’re considering using it as such.

First, some background. Prompted by its potential abuse, the federal government initially banned marijuana in the 1930s. The U.S. Controlled Substances Act, passed in 1970, now lists marijuana as a Schedule I drug, regarding it as having a high potential for abuse and no medical benefit. With growing public acceptance of the drug, however, the federal government has effectively ceded regulation of marijuana to the states. Because of the federal classification, few studies exist of marijuana’s medical value, making it hard to draw sound conclusions about its medical benefits.

Available research shows that marijuana has benefits for symptoms associated with some conditions, among them spasticity (spasms) from multiple sclerosis, chronic pain, pain from neuropathy, nausea or vomiting from chemotherapy, and inflammatory bowel disease. It also stimulates the appetite of patients with cancer-associated anorexia and in HIV patients with significant muscle wasting. Many patients believe it also helps with glaucoma because it lowers the pressure in the eyes, but there is no evidence that marijuana helps with the symptoms of glaucoma, and newer medicines are more effective for the condition.

Dosage and concentration remain major concerns. No guidelines on dosage exist for any condition, and different marijuana plants have different concentrations of THC, the drug’s active ingredient that gives it its narcotic and psychoactive effects.

While marijuana appears to have some benefits, research shows that clear harms are associated with its chronic use. It may worsen anxiety and depression, induce psychosis, and cause cognitive difficulties because of its effects on the brain. Cognitive effects are especially worrisome in adolescents and young adults whose brains are still developing. Chronic users trying to stop may also experience withdrawal symptoms, much like those of nicotine withdrawal.

The majority of people who use marijuana do not become addicted, but 9% of adults and 17% of teenagers do. Those percentages may be low, but considering that marijuana is the most commonly used illicit drug in the U.S., with more than 18 million users, a small fraction of a large number can still be a very large number.

Patients considering marijuana as medicine should first talk with a physician who knows them well. We suggest starting with your primary-care doctor. If you’re under the care of specialists, such as a pain-management physician or oncologist, talk with him or her, too. All physicians treating you should know if you’re using marijuana for medical reasons, as it could interact with other medications.

It’s important to understand that physicians in Massachusetts will not be prescribing marijuana for patients. Rather, they will be certifying that a patient has a ‘debilitating medical condition’ eligible for medical marijuana according to state regulations. Also, physicians who are generally opposed to smoking are not required to certify any patient, and some may decline to do so because of the federal ban or limited clinical evidence.

Whatever role marijuana may have as medicine, we believe it should be a supplement to standard treatment. There isn’t any condition for which it should be the first line of therapy.

Dr. Alan Ehrlich is senior deputy editor of DynaMed, a clinical reference tool that examines medical articles for clinical relevance and scientific validity. Dr. Kevin Hill is director of the Substance Abuse Consultation Service in the Division of Alcohol and Drug Abuse at McLean Hospital in Belmont. This article is a service of the Mass. Medical Society.