Exploring the Science Behind Medical Marijuana

Marijuana has been used to ease the pain of multiple sclerosis, to reduce nausea and stimulate appetite in cancer patients receiving chemotherapy, and to treat glaucoma. Many people also say it relieves symptoms of PTSD, fibromyalgia, irritable bowel syndrome, and Crohn’s disease.

However, the evidence is limited because of strict governmental restrictions on research. Observational studies and results from test-tube or animal experiments may look promising, but they differ from clinical trials that would validate the findings.


Tetrahydrocannabinol (THC) is the main psychoactive component of marijuana. It produces its intoxicating effects by binding to cannabinoid receptors in the brain.

It’s a powerful pain reliever, and studies show it reduces chronic pain from many conditions, including multiple sclerosis, peripheral neuropathy (nerve pain from diabetes or spinal cord injury), fibromyalgia, rheumatoid arthritis, and others. It also appears to ease muscle spasms in people with multiple sclerosis and can lessen tremors from Parkinson’s disease.

However, THC concentrations vary widely among medical marijuana products sold at dispensaries. Higher-potency strains can have more side effects than lower ones. For example, high-THC products may increase the likelihood of a psychotic reaction. And they might cause you to build up a tolerance faster than low-THC cannabis, so you need more of it to get the same effect.


With more states legalizing marijuana for medicinal use, researchers are working to keep up. But evaluating medical marijuanas Canada isn’t easy, hampered by a lack of official data on it and the wide variety of available products. Observational studies and animal or test-tube studies can sound promising, but they don’t translate directly to people with real health concerns.

The FDA has approved the cannabinoids CBD (Epidiolex) and dronabinol to treat certain forms of severe epilepsy. It also has approved a product that contains THC and nabilone to reduce nausea and vomiting related to cancer chemotherapy and to stimulate appetite in people with AIDS. Research suggests marijuana may help ease nerve pain and muscle spasms associated with multiple sclerosis, and it may improve sleep in people who have trouble sleeping because of arthritis, fibromyalgia, or other conditions.


The cannabis plant contains dozens of chemicals called cannabinoids. Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have psychoactive effects. Others, like cannabichromene, cannabigerol, and tetrahydrocannabinovarin, have less psychoactive effects but still exert biological activity.

Studies of these chemicals are ongoing. But there’s enough evidence to support using marijuana for some health problems, such as pain from rheumatoid arthritis or multiple sclerosis. It also eases anxiety and sleeplessness. It controls nausea and vomiting associated with cancer chemotherapy and stimulates appetite in people who don’t eat enough because of AIDS or other illnesses.

Two FDA-approved THC medications are dronabinol (Marinol) and nabilone (Cesamet). They treat nausea and loss of appetite from some diseases, including HIV/AIDS. They also reduce pressure in the eye (glaucoma). But they don’t improve symptoms of tremors or help with arthritis.


Flavonoids are a diverse group of natural compounds produced in the plant kingdom, including fruits, vegetables, tea, red wine, and cannabis. They are responsible for the vivid colors of plants, and their antioxidant properties help protect against oxidative stress.

Flavonoid molecules also have a variety of medicinal effects. Flavonoids like quercetin are found in capers, kale, and apples. They provide anti-inflammatory, antimutagenic (i.e., can prevent changes in DNA sequences), antifungal and antiviral activities.

The researchers profiled the secondary metabolites in cannabis inflorescences, leaves, stem barks, and roots from three chemovars. The chemical fingerprints of the cannabis chemovars are similar and correlated with their vernacular names, but the terpenoids and flavonoids vary significantly between chemovars. These differences may underlie the traditional medicinal use of each cannabis plant part in a given culture.


Terpenes give marijuana (and other plants) its smell and flavor. They also have a wide range of physiological and therapeutic effects—alone or in conjunction with cannabinoids.

The terpenes myrcene and pinene are responsible for the pine-like aroma associated with some cannabis strains. Myrcene is known for its overall body relaxation, while pinene may help relieve pain.

Caryophyllene is a spicy and woody terpene found in black pepper, cloves, and herbs such as oregano, basil, and rosemary. It acts as a cannabinoid by binding to the CB2 receptors in the brain, and research suggests it may reduce stress, anxiety, and depression. It has also been shown to help alleviate symptoms of inflammatory conditions like arthritis and Crohn’s disease.

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