Managing cancer symptoms with medical marijuana

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on February 28, 2022.

Cancer patients who are experiencing symptoms like pain, nausea and appetite loss may be interested in learning whether medical marijuana can help ease these symptoms and improve quality of life. Before trying medical marijuana, it’s a good idea to understand what it is, what the research says about it and whether it’s legal to use.  

What is marijuana/weed?

Marijuana, or weed, is composed of the dried leaves and flowers of the Cannabis sativa plant, which grows around the world in warm and tropical climates. Currently listed by the U.S. Drug Enforcement Administration as a Schedule I controlled substance, marijuana cannot be legally prescribed, sold or purchased under federal law. However, it’s legal in some states for both recreational and medical use, including cancer treatment. The U.S. Food and Drug Administration (FDA) hasn’t approved the plant for medical use.

Still, the use of marijuana for cancer presents an evolving area of experimentation and research. Even with more states implementing medical marijuana laws, questions remain about the legitimate use of marijuana for medical conditions. For cancer patients in particular, medical marijuana may offer an interesting symptom management option. But due to the lack of clinical evidence currently available, many health care providers advise patients to proceed with caution and thoroughly discuss available options with their physician prior to beginning treatment.

Medical marijuana is purported to help cancer patients ease the side effects of the disease and its treatment. What are the facts, and the evidence, behind the claims?

What are cannabinoids?

Marijuana, also called pot, cannabis, ganja, and grass (among other names), contains biologically active compounds called cannabinoids. These include delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), among others. While THC is psychoactive, or mind-altering (which means it causes a "high" feeling), CBD is not. Cannabinoids vary in amount depending on the strain, or type of marijuana. Different strains have different effects based on the ration quantity of specific cannabinoids present.

Just a few cannabinoid drugs are FDA-approved. They are:

  • Dronabinol (Marinol®, Syndros®), a gelatin capsule that contains a synthetic THC and is used to treat nausea and vomiting in cancer patients undergoing chemotherapy and anorexia and weight loss in HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) patients
  • Nabilone (Cesamet®), a synthetic cannabinoid that’s also used to treat nausea and vomiting symptoms of chemotherapy and works similarly to THC
  • Cannabidiol (Epidiolex), which contains CBD to help treat seizures related to two rare epilepsy disorders (Lennox-Gastaut syndrome and Dravet syndrome)

The cannabinoid drug nabiximols, an oral spray, is not yet FDA-approved, but some research has shown promise in treating pain from cancer, muscle spasms and multiple sclerosis (MS).

How do cannabinoids affect cancer symptoms?

THC in marijuana may help relieve symptoms of pain and nausea in cancer patients. CBD reduces inflammation and serves as an antioxidant. Marijuana may be eaten, smoked, inhaled or vaped, and its effects differ by the method used.

  • Edible marijuana: When taken orally in the form of oils, food or drinks, THC takes longer to be absorbed and processed by the liver. It’s hard to gauge how much THC is present in foods with marijuana, and how much THC would cause overdose symptoms.
  • Inhaled marijuana: When smoked or vaped, the THC in marijuana quickly enters the bloodstream and travels to the brain. Its effects are much faster than when taken orally, but they also fade more quickly.

When it comes to marijuana and cancer, some studies have found the plant may lessen symptoms of nausea and vomiting from chemotherapy, and it may help treat neuropathic pain caused by nerve damage. Cancer patients who use marijuana often need less pain medication, according to the ACS.

Is there a place for marijuana in medicine?

The active component of marijuana (cannabis) is tetrahydrocannabinol (THC). In some people, THC has the effect of controlling nausea, increasing appetite and lessening pain. The synthetic derivative of THC (dronabinol) is manufactured and sold as a Schedule III drug, defined as having low to moderate potential for physical or psychological dependence, and may be prescribed by a physician. These medications are strictly regulated by the FDA for purity, effectiveness and safety.

The FDA approves the use of dronabinol for anorexia related to AIDS wasting syndrome, as well as for refractory chemotherapy-induced nausea and vomiting. THC may also be obtained by smoking or eating the marijuana (cannabis) plant. However, the dosage of these plant-based forms is variable and not regulated by the FDA. This variability may lead to decreased effectiveness or increased side effects among users of marijuana.

What are the marijuana side effects?

Although THC may help reduce nausea or increase appetite, its side effects may also include the inability to think clearly or concentrate and, over the long-term, may include mental disorders such as schizophrenia, depression and/or bipolar disorder. In addition, respiratory complications such as chronic bronchitis could develop as a side effect of THC.

How does marijuana interact with other medications?

As with any medicine, marijuana may amplify side effects of other medications. It is important to discuss the use of medicines and supplements with a physician and ask about potential side effects or interactions.

Does insurance pay for medical marijuana?

Although states have passed laws permitting the use of medical marijuana, under federal law, marijuana continues to be an illegal Schedule I drug, meaning that it is considered to have a high potential for abuse and is not recognized for medicinal use. Because of this, marijuana cannot be used in hospital settings or dispensed at licensed pharmacies. Insurance companies do not cover the cost of medical marijuana, but most will cover the use of the pharmaceutical dronabinol, which contains the active component THC.

What is the medical evidence supporting medical marijuana?

Aside from anecdotal reports, very little medical evidence is available to support the use of medical marijuana. Only a small number of controlled studies have examined the benefits and risks of marijuana use. At this time, it is difficult to make a medical judgment regarding the use of medical marijuana with so little evidentiary details on which to base it.

How do I get medical marijuana?

Regulation of medical marijuana possession and use varies from state to state. In many states, patients can get medical marijuana at a dispensary, but only with a medical marijuana card.

Ultimately, medical decision-making is shared between individual patients and their physicians. If a physician determines that a medical indication exists for its use, the method of obtaining the product varies depending on that state’s laws. It's up to the patient and his or her physician to determine and comply with all state and federal regulations.

Learn more about pain management therapies being used as alternatives to opioids.

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