The Takeaway

In recent years, the medical marijuana policy landscape has changed dramatically. Existing evidence supports the drug’s therapeutic effects for pain management and alleviating the effects of certain other chronic illnesses under specific conditions. More recently, findings regarding medical marijuana have suggested it may play a role in treating certain conditions, improving quality of life, and reducing opioid use, which could be helpful as states and the nation consider ways to manage the overdose crisis. Greater research is needed to determine the full range of marijuana’s medicinal usage, and it is key to take into consideration its potential for adverse side effects for adolescents and adults alike, including addiction.  

The Evidence

How medical marijuana works 
Marijuana has been used as a drug, both medicinally and recreationally, for several hundred years. The use of marijuana for medical purposes involves the ingestion or inhalation of cannabinoids, chemical substances found in the cannabis plant.  

The two main cannabinoids in the cannabis plant are delta-9-tetrahydrocannabinol (more commonly known as THC) and cannabidiol (more commonly known as CBD). THC is responsible for the strong psychoactive effects associated with marijuana use, while CBD is a non-psychoactive cannabinoid, is thought to show potential therapeutic effects. THC acts by binding to the brain’s cannabinoid receptors, causing many different effects including short-term memory impairment, appetite stimulation, pain reduction, nausea reduction, and potential lightheadedness and euphoria. CBD similarly has great therapeutic potential, including pain relief, anxiety reduction, nausea suppression, and anti-inflammatory properties. Unlike THC, CBD does not cause psychoactive effects, shows little to no potential for misuse in frequent marijuana smokers, and can be an effective treatment for cannabis withdrawal syndrome. 

(A quick note on terms. “Cannabis” refers to any and all products derived from the cannabis plant. “Marijuana” refers to parts or products of the cannabis plant that contain substantial amounts of THC). 

Potential benefits of medical marijuana 
Evidence shows that cannabinoids may be effective for use in treating those with chronic pain, neuropathic pain, and multiple sclerosis. Similarly, though its lasting effects have not yet been proven, smoking marijuana has seen to be effective for chronic neuropathic pain. Medications with cannabinoids, such as dronabinol, show the same pain reduction but with fewer negative effects than smoking may cause. For cancer patients, medical marijuana has been shown to have the potential to reduce nausea and vomiting among those receiving chemotherapy. CBD and other cannabinoids may have potential therapeutic effects for the treatment of sleep disorders like insomnia. Medical marijuana use has been associated with lower use of certain prescription drugs (this includes non-opioid pain medication, antidepressants, anti-seizure medication, and benzodiazepines). 

Some research has shown that cannabinoids‘ pain reduction effects may lead to marijuana being used as a substitute for opioids. Among people who use drugs and have chronic pain, daily marijuana use has been shown to be associated with lower opioid use. Similarly, at a macro level, medical marijuana laws have previously been associated with a decrease in opioid overdoses in the states where they are implemented, but the evidence here is mixed. 

There is currently one FDA-approved medication derived from natural CBD, used in severe seizure conditions, and three FDA-approved medications which contain synthetic cannabinoids and ar used to treat nausea and increase appetite. Despite these approved medications, guidelines for the commercial use of CBD are still in progress, though this may change in the near future as the FDA issues new guidance.  Use of certain cultivars (a type of plant-made by selective breeding) and parts of the marijuana plant, both personally and for research, is restricted under the Controlled Substances Act. This can pose challenges and barriers when trying to conduct research on the plant. (You can read more about this here).  

Potential side effects of medical marijuana 
Provider opinions about medical marijuana are mixed, however most reflect a desire for more information about the potential clinical benefits and side effects of the drug.  

Marijuana, like any drug, including FDA-approved medications, can have several adverse physical and mental health side effects. Some of these side effects are dependent on the method of consumption, which is important for patients and providers to discuss when making decisions about medical marijuana. Depending on the quantity consumed and duration of use, smoking marijuana can have some negative impacts on physical health. Individuals who currently smoke marijuana have twice the odds of experiencing episodes of chronic bronchitis than individuals who do not smoke at all, an effect particularly noted among HIV-positive individuals. Some research suggests that there is a correlation between smoking cannabis and ischemic and hemorrhagic cerebrovascular diseases, which can contribute to cerebral stroke. Marijuana use has been associated with tobacco use, however it’s important to note that marijuana smoking tends to have a far lower, or even non-significant, risk of lung and upper respiratory tract cancers compared to tobacco smoking.  

Smoking marijuana has also been associated with negative mental health impacts. Daily marijuana smoking is often associated with earlier onset of psychosis compared to no use, and an increase in use can be particularly psychosis-inducing among individuals with schizophrenia. However, there is insuffient information to conclude the risk associated with marijuana use and pscyhiotic symptoms. There is also a potential association between marijuana use and violence – this effect is particularly evident among patients with PTSD or psychological illness. There is also a significant association between cannabis use and greater anxiety, however there is no firm evidence on whether or not this is causal.  

One of marijuana’s most incontestable effects is that on driving: the odds of being involved in a car accident increases approximately two-fold in the hour after smoking marijuana. Driving under the influence of cannabis (from any form of consumption) has been shown to multiply the risk of fatal car accident 1.6 times. Similarly, select states that have implemented medical marijuana laws have seen an increase in the proportion of fatally injured drivers who test positive for cannabinoids, however this is by no means the case in the majority of states. 

Marijuana, like many drugs, also has the potential for addiction. Medical marijuana laws have been associated with greater substance use disorder treatment use by pregnant women, for marijuana use, as well as for alcohol use and cocaine use. 

It’s important for both providers and patients to keep in mind these side effects when considering medical marijuana as a potential option. 

Medical marijuana and young people 
In recent years, there has been growing interest in using cannabinoids as a treatment option for certain childhood epilepsy, however, the evidence here is not yet compelling, and it is important to recognize that marijuana has side effects that can be particularly impactful in young people. Starting marijuana use during adolescence is associated with a lifetime decline in IQ and general cognitive functioning, even with sustained abstinence in adulthood. Similarly, adolescents appear to be more negatively affected by heavy marijuana use than adults, particularly in regard to learning and memory. Research has still not reached a conclusion as to whether some of these effects may be due to other confounding factors, such as pre-existing personality types or mental impairment. While medical marijuana or cannabinoid medications can be valuable for certain conditions, it is important to not conflate the use of a drug for specific medical purposes as an indication that the drug is a safe recreational activity. 

Because of marijuana’s strong potential side effects among teens, particular care should be taken when considering medical marijuana use in in this population. Providers and families will need to jointly decide if the potential benefits of medical marijuana outweigh the potential side effect for their teen(s). 

Historically, there has been a common belief that marijuana is a ‘gateway drug’, meaning that using it will lead individuals to start using other “harder” substances, or that marijuana use will make it easier for individuals to become addicted to illegal substances, including opioids. However, this perspective is generally not supported by research. While marijuana use has been linked to nicotine addiction in adolescents, and other drugs or alcohol, this does not mean marijuana use causes an individual to use other drugs. Instead, research has shown that a significant portion of this connection between early marijuana use and future substance use or addiction to other drugs can be due to other common factors, including genetic and socio-environmental influences, and co-occurring psychiatric illness.  

Medical marijuana and the law  
Marijuana is not legal according to federal law, however, many state laws have been implemented to allow the use of medical marijuana. Although regulations on the use of marijuana differ from state to state, all such laws allow the use of and access to marijuana for medical purposes without state penalties. Specifically, at the time of writing, 11 states have established laws legalizing CBD for medical use, and medical marijuana for ingestion via smoking is allowed via comprehensive program in 36 states, D.C., Guam, Puerto Rico, and the US Virgin Islands. While policies vary from state to state, in practice, this often means that a patient seeking to obtain medical marijuana must first register for a medical card, before they are able to purchase medical marijuana from a regulated, state-licensed dispensary. As more states look to implement medical marijuana legalization, the House of Representatives may at some point vote to remove marijuana as a Schedule I drug from the Controlled Substance Act, in order to reflect its therapeutic benefits.  

Final Thoughts

It is evident that the use of medical marijuana may be beneficial for pain reduction and treatment of certain conditions, however, it is not a cure-all. Like any drug, medical marijuana has potential side effects, so it is important for users to speak to their doctor to determine if medical marijuana is right for them. Ultimately, the evidence demonstrates the usefulness of medical marijuana in treating certain health conditions and decreasing the use of opioids, however, more research is needed to determine the full range of therapeutic benefits and negative side effects.