What is medical marijuana?
The term medical marijuana refers to using the whole, unprocessed marijuana plant or its basic extracts to treat symptoms of illness and other conditions. The U.S. Food and Drug Administration (FDA) has not recognized or approved the marijuana plant as medicine.
However, scientific study of the chemicals in marijuana, called cannabinoids, has led to two FDA-approved medications that contain cannabinoid chemicals in pill form. Continued research may lead to more medications.
Because the marijuana plant contains chemicals that may help treat a range of illnesses and symptoms, many people argue that it should be legal for medical purposes. In fact, a growing number of states have legalized marijuana for medical use.
Why isn’t the marijuana plant an FDA-approved medicine?
The FDA requires carefully conducted studies (clinical trials) in hundreds to thousands of human subjects to determine the benefits and risks of a possible medication. So far, researchers haven’t conducted enough large-scale clinical trials that show that the benefits of the marijuana plant (as opposed to its cannabinoid ingredients) outweigh its risks in patients it’s meant to treat.
Read more about the various physical, mental, and behavioral effects of marijuana in our Marijuana Drug Facts.
Can Medical Marijuana Legalization Decrease Prescription Opioid Problems?
Some preliminary studies have suggested that medical marijuana legalization might be associated with decreased prescription opioid use and overdose deaths, but researchers don’t have enough evidence yet to confirm this finding. For example, one NIDA-funded study suggested a link between medical marijuana legalization and fewer overdose deaths from prescription opioids.1 But this study didn’t show that medical marijuana legalization caused the decrease in deaths or that pain patients changed their drug-taking behavior.2,3
A more detailed NIDA-funded analysis showed that legally protected medical marijuana dispensaries, not just medical marijuana laws, were also associated with a decrease in the following:4
• opioid prescribing
• self-reports of opioid misuse
• treatment admissions for opioid addiction
Additionally, data suggests that medical marijuana treatment may reduce the opioid dose prescribed for pain patients,5,6 and a recent study showed that availability of medical marijuana for Medicare patients reduced prescribing of medications, including opioids, for their pain.7 NIDA is funding additional studies to determine the link between medical marijuana use and the use or misuse of opioids for pain.
What are cannabinoids?
Cannabinoids are chemicals related to delta-9-tetrahydrocannabinol (THC), marijuana’s main mind-altering ingredient that makes people “high.”
The marijuana plant contains more than 100 cannabinoids. Scientists as well as illegal manufacturers have produced many cannabinoids in the lab. Some of these cannabinoids are extremely powerful and have led to serious health effects when misused. Read more in our Synthetic Cannabinoids (K2/Spice) DrugFacts.
CBD and Childhood Epilepsy
There is growing interest in the marijuana chemical cannabidiol (CBD) to treat certain conditions such as childhood epilepsy, a disorder that causes a child to have violent seizures. Therefore, scientists have been specially breeding marijuana plants and making CBD in oil form for treatment purposes. These drugs aren’t popular for recreational use because they aren’t intoxicating.
The body also produces its own cannabinoid chemicals. They play a role in regulating pleasure, memory, thinking, concentration, body movement, awareness of time, appetite, pain, and the senses (taste, touch, smell, hearing, and sight).
Are People with Health- and Age-Related Problems More Vulnerable to Marijuana’s Risks?
State-approved medicinal use of marijuana is a fairly new practice. For that reason, marijuana’s effects on people who are weakened because of age or illness are still relatively unknown. Older people and those suffering from diseases such as cancer or AIDS could be more vulnerable to the drug’s harmful effects, but more research is needed.
How might cannabinoids be useful as medicine?
Currently, the two main cannabinoids from the marijuana plant that are of medical interest are THC and CBD.
THC can increase appetite and reduce nausea. THC may also decrease pain, inflammation (swelling and redness), and muscle control problems.
Unlike THC, CBD is a cannabinoid that doesn’t make people “high.” It may be useful in reducing pain and inflammation, controlling epileptic seizures, and possibly even treating mental illness and addictions.
Many researchers, including those funded by the National Institutes of Health (NIH), are continuing to explore the possible uses of THC, CBD, and other cannabinoids for medical treatment.
For instance, recent animal studies have shown that marijuana extracts may help kill certain cancer cells and reduce the size of others. Evidence from one cell culture study with rodents suggests that purified extracts from whole-plant marijuana can slow the growth of cancer cells from one of the most serious types of brain tumors. Research in mice showed that treatment with purified extracts of THC and CBD, when used with radiation, increased the cancer-killing effects of the radiation.8
Scientists are also conducting preclinical and clinical trials with marijuana and its extracts to treat symptoms of illness and other conditions, such as:
• diseases that affect the immune system, including:
• multiple sclerosis (MS), which causes gradual loss of muscle control
• substance use disorders
• mental disorders
Read more about the NIH’s marijuana research:
• Marijuana and Cannabinoid Research at NIDA
• NIH Research on Marijuana and Cannabinoids
Using Medical Marijuana During and After Pregnancy
Some women report using marijuana to treat severe nausea they have during pregnancy. But there’s no research that shows that this practice is safe, and doctors generally don’t recommend it.
Pregnant women shouldn’t use medical marijuana for nausea or any other reason without first checking with their health care provider. Animal studies have shown that moderate amounts of THC given to pregnant or nursing women could have long-lasting effects on the child, including abnormal patterns of social interactions9 and learning issues.10,11
What medications contain cannabinoids?
Two FDA-approved drugs, dronabinol and nabilone, contain THC.
They treat nausea caused by chemotherapy and increase appetite in patients with extreme weight loss caused by AIDS. Continued research might lead to more medications.
The United Kingdom, Canada, and several European countries have approved nabiximols (Sativex®), a mouth spray containing THC and CBD. It treats muscle control problems caused by MS, but it isn’t FDA-approved.
Epidiolex, a CBD-based liquid drug to treat certain forms of childhood epilepsy, is being tested in clinical trials but isn’t yet FDA-approved.
Points to Remember
• The term medical marijuana refers to treating symptoms of illness and other conditions with the whole, unprocessed marijuana plant or its basic extracts.
• The FDA has not recognized or approved the marijuana plant as medicine.
• However, scientific study of the chemicals in marijuana called cannabinoids has led to two FDA-approved medications in pill form, dronabinol and nabilone, used to treat nausea and boost appetite.
• Cannabinoids are chemicals related to delta-9-tetrahydrocannabinol (THC), marijuana’s main mind-altering ingredient.
• Currently, the 2 main cannabinoids from the marijuana plant that are of interest for medical treatment are THC and cannabidiol (CBD).
• The body also produces its own cannabinoid chemicals.
• Scientists are conducting preclinical and clinical trials with marijuana and its extracts to treat symptoms of illness and other conditions.
For more information about marijuana and its health effects, visit our:
• Marijuana Research Report
• Marijuana DrugFacts
1. Bachhuber MA, Saloner B, Cunningham CO, Barry CL. Medical cannabis laws and opioid analgesic overdose mortality in the United States, 1999-2010. JAMA Intern Med. 2014;174(10):1668-1673. doi:10.1001/jamainternmed.2014.4005.
2. Finney JW, Humphreys K, Harris AHS. What ecologic analyses cannot tell us about medical marijuana legalization and opioid pain medication mortality. JAMA Intern Med. 2015;175(4):655-656. doi:10.1001/jamainternmed.2014.8006.
3. Bachhuber MA, Saloner B, Barry CL. What ecologic analyses cannot tell us about medical marijuana legalization and opioid pain medication mortality–reply. JAMA Intern Med. 2015;175(4):656-657. doi:10.1001/jamainternmed.2014.8027.
4. Powell D, Pacula RL, Jacobson M. Do Medical Marijuana Laws Reduce Addiction and Deaths Related to Pain Killers?RAND Corporation; 2015. http://www.rand.org/content/dam/rand/pubs/working_papers/WR1100/WR1130/RAND_WR1130.pdf. Accessed April 6, 2017.
5. Abrams DI, Couey P, Shade SB, Kelly ME, Benowitz NL. Cannabinoid-opioid interaction in chronic pain. Clin Pharmacol Ther. 2011;90(6):844-851. doi:10.1038/clpt.2011.188.
6. Lynch ME, Clark AJ. Cannabis reduces opioid dose in the treatment of chronic non-cancer pain. J Pain Symptom Manage. 2003;25(6):496-498.
7. Bradford AC, Bradford WD. Medical Marijuana Laws Reduce Prescription Medication Use In Medicare Part D. Health Aff Proj Hope. 2016;35(7):1230-1236. doi:10.1377/hlthaff.2015.1661.
8. Scott KA, Dalgleish AG, Liu WM. The combination of cannabidiol and Δ9-tetrahydrocannabinol enhances the anticancer effects of radiation in an orthotopic murine glioma model. Mol Cancer Ther. 2014;13(12):2955-2967. doi:10.1158/1535-7163.MCT-14-0402.
9. Trezza V, Campolongo P, Cassano T, et al. Effects of perinatal exposure to delta-9-tetrahydrocannabinol on the emotional reactivity of the offspring: a longitudinal behavioral study in Wistar rats. Psychopharmacology (Berl). 2008;198(4):529-537. doi:10.1007/s00213-008-1162-3.
10. Antonelli T, Tomasini MC, Tattoli M, et al. Prenatal exposure to the CB1 receptor agonist WIN 55,212-2 causes learning disruption associated with impaired cortical NMDA receptor function and emotional reactivity changes in rat offspring. Cereb Cortex N Y N 1991. 2005;15(12):2013-2020. doi:10.1093/cercor/bhi076.
11. Mereu G, Fà M, Ferraro L, et al. Prenatal exposure to a cannabinoid agonist produces memory deficits linked to dysfunction in hippocampal long-term potentiation and glutamate release. Proc Natl Acad Sci U S A. 2003;100(8):4915-4920. doi:10.1073/pnas.0537849100.
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This page was last updated April 2017
Part 2 NIH Research Report
NIH Is marijuana safe and effective as medicine?
The potential medicinal properties of marijuana and its components have been the subject of research and heated debate for decades.
THC itself has proven medical benefits in particular formulations.
The U.S. Food and Drug Administration has approved THC-based medications, dronabinol (Marinol®) and nabilone (Cesamet®), prescribed in pill form for the treatment of nausea in patients undergoing cancer chemotherapy and to stimulate appetite in patients with wasting syndrome due to AIDS.
In addition, several other marijuana-based medications have been approved or are undergoing clinical trials. Nabiximols (Sativex®), a mouth spray that is currently available in the United Kingdom, Canada, and several European countries for treating the spasticity and neuropathic pain that may accompany multiple sclerosis, combines THC with another chemical found in marijuana called cannabidiol (CBD).
CBD does not have the rewarding properties of THC, and anecdotal reports indicate it may have promise for the treatment of seizure disorders, among other conditions.
A CBD-based liquid medication called Epidiolex is currently being tested in the United States for the treatment of two forms of severe childhood epilepsy, Dravet syndrome and Lennox-Gastaut syndrome.
Researchers generally consider medications like these, which use purified chemicals derived from or based on those in the marijuana plant, to be more promising therapeutically than use of the whole marijuana plant or its crude extracts.
Development of drugs from botanicals such as the marijuana plant poses numerous challenges. Botanicals may contain hundreds of unknown, active chemicals, and it can be difficult to develop a product with accurate and consistent doses of these chemicals.
Use of marijuana as medicine also poses other problems such as the adverse health effects of smoking and THC-induced cognitive impairment. Nevertheless, a growing number of states have legalized dispensing of marijuana or its extracts to people with a range of medical conditions.
An additional concern with “medical marijuana” is that little is known about the long-term impact of its use by people with health- and/or age-related vulnerabilities—such as older adults or people with cancer, AIDS, cardiovascular disease, multiple sclerosis, or other neurodegenerative diseases. Further research will be needed to determine whether people whose health has been compromised by disease or its treatment (e.g., chemotherapy) are at greater risk for adverse health outcomes from marijuana use.
Medical Marijuana Legalization and Prescription Opioid Use Outcomes
NIDA funded two recent studies that explored the relationship between marijuana legalization and adverse outcomes associated with prescription opioids. The first found an association between medical marijuana legalization and a reduction in overdose deaths from opioid pain relievers, an effect that strengthened in each year following the implementation of legislation.78 The population-based nature of this study does not establish a causal relationship or give evidence for changes in pain patient behavior.79,80
The second NIDA-funded study, a more detailed analysis by the RAND Corporation, showed that legally protected access to medical marijuana dispensaries is associated with lower levels of opioid prescribing, lower self-report of nonmedical prescription opioid use, lower treatment admissions for prescription opioid use disorders, and reduction in prescription opioid overdose deaths.81Notably, the reduction in deaths was present only in states with dispensaries (not just medical marijuana laws) and was greater in states with active dispensaries.
Research into the effects of cannabis on opioid use in pain patients is limited, but data suggest that medical cannabis treatment may reduce the dose of opioids required for pain relief.82,83 In addition to its research portfolio on the roles of the cannabinoid and opioid systems in pain, NIDA is funding additional studies that will provide data relating to medical marijuana and opioids:
• effects of access to medical marijuana on substance use, including nonmedical use of prescription opioids (project numbers DA031816-05, DA039293-01A1, DA037341-02, DA032693-04)
• mental and physical functioning of a cohort of pain patients seeking medical marijuana treatment (DA033397-03)
• the impact of medical marijuana policies on health outcomes (DA034067-03)
Another recent study analyzed Medicare prescription drug coverage data and found that availability of medical marijuana significantly reduced prescribing of medications used for conditions that medical marijuana can treat, including opioids for pain.84 Overall savings for all prescription drugs were estimated to be $165.2 million in 2013.
Though none of these studies are definitive, they cumulatively suggest that medical marijuana products may have a role in reducing the use of opioids needed to control pain. More research is needed to investigate this possibility.
This page was last updated August 2017