Medical Marijuana: Benefits, Risks & State Laws

medical marijuana
Organic Cannabis indica purchased from a Medical Cannabis dispensary in California.
Credit: Mjpresson

With medical marijuana legal in 22 states and the District of Columbia — in addition to the legalization of recreational marijuana in Colorado and Washington state — more people may turn to marijuana as a treatment option for many ailments. However, the medicinal use of cannabis is not new; it can be traced back to ancient physicians who prescribed marijuana for pain relief, digestive problems and psychological disorders, among other conditions.

As early as 2737 B.C., the emperor of China, Shen Neng, touted cannabis tea as a treatment for gout, rheumatism, malaria and even poor memory, writes Mitch Earleywine, a professor of psychology at the State University of New York at Albany who researches drugs and addiction, in "Understanding Marijuana: A New Look at the Scientific Evidence" (Oxford University Press, 2005). The drug's popularity as a medicine spread throughout Asia, the Middle East and then to Africa and India, where Hindu sects used it for pain and stress relief.

By the late 18th century, early editions of American medical journals recommend hemp seeds and roots for the treatment for a variety of conditions, including inflamed skin, incontinence and venereal disease. William O'Shaughnessy, an Irish doctor, popularized medical use of cannabis in England and America, Earleywine writes.

There was a dramatic shift in attitude toward medicinal uses of marijuana and other drugs by the 19th century. By that time, as much as 5 percent of the U.S. population became addicted to morphine, an unknown ingredient in treatments touted by traveling medicine men.

As a result, the Food and Drug Administration was formed in 1906. While marijuana wasn’t specifically mentioned in the original FDA guidelines, the move to control chemical substances curtailed its use as treatment.

By 1937, marijuana use, medical or otherwise, has been banned in 37 states. Also in 1937, the Marihuana Tax Act [sic] imposed such high taxes on physicians prescribing cannabis, retail pharmacists selling cannabis, and those cultivating medical cannabis that it essentially fell out of favor as a treatment.

Health benefits

Medical marijuana is available in several different forms. It can be smoked, ingested in a pill form or an edible version can be added to foods such as brownies, cookies and chocolate bars.

Cannabis contains about 60 active ingredients called cannabinoids (chemicals unique to marijuana). The primary psychoactive chemical in marijuana is THC, or tetrahydrocannabinol. THC offers feelings of euphoria and “floating” and has pain-relieving properties. These properties may benefit people with chronic pain, nausea from chemotherapy and the effects of progressive diseases such as glaucoma and multiple sclerosis (MS).

For example, researchers at the American Academy of Neurology found that medical marijuana in the form of pills or oral sprays appeared effective in reducing stiffness and muscle spasms in MS. The medications also eased certain symptoms of MS, such as pain related to spasms, and painful burning and numbness, as well as overactive bladder, according to the study published in the journal Neurology.

One of the most common uses for medical marijuana is to ease the symptoms of nausea from chemotherapy. Two FDA-approved cannabis-based drugs, dronabinol and nabilone, have been shown to reduce chemotherapy-related nausea and vomiting in cancer patients.

Medical marijuana has also been used to treat glaucoma, which is an elevated pressure in the eyeball that can lead to blindness. While smoking marijuana may reduce intraocular pressure, some debate the effectiveness of marijuana use because it must be consumed numerous times during the day to have the desired effect, which can have mood-altering implications and impact the patient’s ability to function, according to the American Cancer Society. A well-known effect of marijuana use is the “munchies,” so it has also been used to stimulate appetite among HIV/AIDS patients and others who have a suppressed appetite due to a medical condition or treatment.

Cannabidiol (CBD) is a non-psychoactive component of marijuana that has therapeutic benefits without the feeling of being stoned. For example, a 2012 study published in the journal Translational Psychiatry found that cannabidiol may be effective in treating schizophrenia. In the study at the University of Cologne, 42 patients randomly received either cannabidiol or amisulpride, an effective drug used for the treatment of schizophrenia, for 28 days. Comparison of the clinical effects found "no relevant difference" between the two treatments.

Health risks

Marijuana does have side effects. THC binds to cannabinoid receptors, which are concentrated in areas of the brain associated with thinking, memory, pleasure, coordination and time perception. The effects of marijuana can interfere with attention, judgment and balance.

Marijuana also suppresses the immune system, which can be damaging to many people, but useful for others with certain health conditions. Although marijuana has been known to decrease pressure within the eyes, a symptom of the condition glaucoma, research has shown that other drugs may be more effective.

Studies have produced conflicting results on whether smoking marijuana carries a significant cancer risk. According to the American Cancer Society, worldwide research into the benefits and side effects of compounds in marijuana is ongoing.

The FDA has not approved marijuana in its plant form as a treatment. During a 2004 congressional testimony, a doctor speaking on behalf of the FDA said marijuana as a “botanical product” is difficult to test for efficacy and safety because the proportions of active chemicals can range greatly from plant to plant. This, he said, can also cause problems for patients trying to use marijuana.  But he added that the FDA “will be receptive to sound, scientifically based research into the medicinal uses of botanical marijuana and other cannabinoids.”

Medical marijuana availability: State by state

Medical marijuana "prescriptions" are termed "recommendations" or "referrals" because of federal laws prohibiting the prescribing of cannabis.

According to the National Conference of State Legislatures, California became the first state to allow the medical use of marijuana in 1996. Currently, 22 states and the District of Columbia have public medical marijuana and cannabis programs.

The states with medical marijuana laws are: Alaska, Arizona, California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, Nevada, New Hampshire, New Jersey, New Mexico, Oregon, Rhode Island, Vermont and Washington.

All 22 states require a doctor’s approval and all but Washington state require an ID card to be shown at the dispensary or enrollment in a patient registry. Many of the states that allow medical marijuana have an online application process.

In most states, patients need to fill out the application, pay a fee and provide identification information. To successfully receive an ID card in most states, patients need a signed statement from a doctor diagnosing the condition and a document stating that medical marijuana is the treatment recommended for the patient’s particular condition and situation.

Most of the laws allow dispensaries and outline specific conditions for which medical marijuana can be prescribed. Thee restrictions also vary by state as to the format and amount of medical cannabis that can be obtained at each visit for personal use.

Another seven states — Alabama, Florida, Kentucky, Mississippi, Tennessee, Utah and Wisconsin — have laws that provide limited access to medical marijuana with low THC/high CBD.

This article is for informational purposes only, and is not meant to offer medical advice.

Lauren Cox contributed to this article.

Pot Quiz: Test Your Marijuana Knowledge, Dude!
You might not think marijuana and quizzes go together, but on the assumption that you arrived at this quiz sober, we pose some serious questions that will require your utmost attention and critical thinking skills. Good luck.
Start the Quiz
marijuana, cooking with hemp
0 of 10 questions complete
Pot Quiz: Test Your Marijuana Knowledge, Dude!
You might not think marijuana and quizzes go together, but on the assumption that you arrived at this quiz sober, we pose some serious questions that will require your utmost attention and critical thinking skills. Good luck.
Start Quiz
marijuana, cooking with hemp
0 of questions complete

Additional resources:

Editor's Recommendations

More from LiveScience