What are the risks and benefits of cannabis (smoking and non-smoking versions)?

Hana Rahman, National Center for Health Research

Intro:

After years of government opposition to marijuana because of its own effects and especially as a gateway drug to other, riskier drugs, it is now legal for recreational use in 24 states and legal for medical uses in 14 states.¹ Of course alcohol and tobacco are legal in all states, but that doesn’t mean it is completely safe. There are many products on the market made from cannabinoids, the more than 100 chemicals that make up cannabis. THC is one of those chemicals and produces psychoactive effects. CBD is another one of those chemicals, and is often sold in the U.S. However, cannabis as well as cannabinoids can cause “Cannabis Use Disorder,” which is the inability to stop consuming cannabis even when it is clearly harming the user.² What does research tell us about the proven benefits and proven risks? Are products sold in dispensaries safer/more beneficial than those grown at home or bought elsewhere?

Smoking cannabis 

Risks 

There are different ways to consume cannabis. The traditional ways of smoking cannabis include cannabis flower ground up and rolled into papers or smoked out of glass pipes or bongs. Smoking cannabis has risks similar to smoking tobacco: chronic bronchitis, lung disease and collapsed lungs in heavy users.³ Long-term practice of smoking cannabis products may also lead to cancers of the lung, oral cavity and throat.³

Aside from the traditional forms of smoking weed, a condition called e-cigarette or vaping associated lung injury (EVALI) is also relevant to cannabis. EVALI has primarily affected young men (70%) in the U.S. and most reported cases have involved vaping THC products.⁵ That study suggests that young men may be more likely than women to have access to cannabis vaping cartridges that could be contaminated with substances such as Vitamin E acetate, ethanol, vegetable glycerine, or pesticides, all of which can increase their risk of EVALI.^5,6

Misuse and overuse of cannabis can also have harmful effects on mental health. We can examine the risks related to cannabis use by looking at the prevalence of Cannabis Use Disorder (CUD), which is listed in the DSM IV, a manual health researchers and professionals use to diagnose mental health disorders and affects about 10% of cannabis users.⁷ Symptoms include cannabis withdrawal which can lead to depression, decreased appetite, restlessness or irritability and are more prevalent among males; however, females reported a shorter time period from onset of cannabis use to onset of cannabis use disorder compared to men. One study showed that females reported greater effects at lower doses of edible cannabis (5 mg), while males reported greater subjective effects at higher doses (15 mg).⁹ This indicates that women may be more likely to experience dependence more quickly than men. This also suggests the need for additional research on safe levels of exposure. One study that followed people for 20 years found that that when compared to those with no cannabis use disorder and no history of head and neck cancers, those with cannabis use disorder were 3.5 times as likely to develop head and neck cancers.³ Although head and neck cancers are relatively rare, such an increase is worrisome and individuals should be aware of these risks.³

Research on the effects of cannabis for symptom relief of physical and mental illnesses is limited and lacks the solid evidence provided for traditional pain medications. Traditional pain medicines have proven to be consistently effective in clinical trials but can rarely pose serious threats to the gastrointestinal, cardiovascular, and renal symptoms when used regularly.¹⁰

Benefits

Despite its many risks, clinical research shows us that cannabis and cannabinoids have many benefits as well. Many users use it for general pain relief, to reduce symptoms of anxiety or depression, or to relieve symptoms of cancer treatment.¹¹ Some cannabinoids cause the user to have psychoactive effects although CBD and some other cannabinoids do not. The only FDA approved cannabis-derived product is Epidiolex, which contains CBD and can only be prescribed from a licensed healthcare provider.¹²

Cancer patients have often used cannabis and cannabinoids such as CBD for nausea and vomiting (21%), anxiety (20%), overall quality of life/well-being (17%), pain (15%), appetite or weight gain (12%), depression (9%), and cancer treatment (4%), according to a survey of adults undergoing chemotherapy in community-based outpatient cancer centers.¹¹ A 30% or greater symptom improvement was reported and retained for at least 4 months.¹¹ Many patients who have pain from previous accidents, and other chronic pain or acute pain have experienced relief when using cannabis in combination with standard pain medication.¹¹

A 2020 review of studies regarding the medical application of cannabis across all major psychiatric disorders indicated support for CBD for reducing social anxiety.¹³  This review also suggested that medicinal cannabis may be beneficial for improving sleep and post-traumatic stress disorder, although the evidence has not been replicated yet so it is considered weak.¹³

In 2018, a California study examining consumer perception of risks and benefits found that most cannabis users believed that smoking cannabis reduced their anxiety and depressions better than any other form of cannabis consumption.¹⁴ Although this may be a placebo effect, it clearly shows that public perception of benefits support the need for better research into the effects of cannabis on mental health. Another study examining the perception of the health risks of cannabis use across Canada and the U.S. found that participants disagreed when asked if cannabis use is also known to worsen respiratory symptoms, and only one-fifth of daily consumers and approximately half of the general population in each jurisdiction agreed with that it would worsen respiratory symptoms.¹⁵  These studies clearly show that better research is needed to educate the public about the risks and benefits of cannabis and cannabinoids.

Non-smoking cannabis 

Risks

Edible cannabis has become increasingly popular for the management of pain and other medical ailments. The biggest risk associated with non-smoking edible options are taking too much at once and not knowing how much is too much or not keeping track of how much was consumed. A Canadian study examining the effect of legalization of cannabis use documented emergency department visits over the course of 7 years, between 2015 and 2022.¹⁶ This study found that there were 2,332 emergency department (ED) visits for cannabis use.¹⁶ These findings suggest that individuals need more information about individual differences on the safe amount of cannabis to consume. Users who came to the EDs reported experiencing psychiatric symptoms and anxiety-induced physical symptoms. This study also found that rates of ED visits related to cannabis use increased significantly after the legalization of edible cannabis. So despite its approval for legal medical use, without proper guidance on dosing, many patients had poor experiences with non-smoking cannabis.

Benefits

Non-smoking cannabis use means no inhalation is occurring, and that is safer for lungs and oral cavities. Additionally, this method of consumption is convenient for those who may use them for chemotherapy/pain relief in hospital or outpatient settings. Non-smoking cannabis products allow patients with preexisting diseases or conditions in the lungs, oral cavity and cardiovascular illnesses to experience relief. If proper dosing is established for the individual, it can reduce some symptoms related to pain, nausea, vomiting and anorexia in patients with different ailments.¹²

How safe are products on the market?

Smoking and non-smoking cannabis products can be purchased at dispensaries. It is important to note that other than Epidiolex, no smoking, vaping and edible cannabis products have been FDA approved and they are not legal under federal law.¹⁷ However, state regulatory practice differs state-to-state.¹⁶ This makes the assessment of “safe” cannabis products more difficult. Nevertheless, several clinical studies have aimed to describe the advantages and disadvantages of different forms of cannabis. As a precaution for users, 2021 studies compiled a list of different forms of cannabis and their effects to be aware of as well as different things to look out for on packaging when determining whether or not a cannabis product is safe for consumption. ^13,17

Conclusions

Studies indicate that there are potential benefits and risks of smoking and nonsmoking cannabis. In addition to cannabis being illegal in many states, cannabis users should realize there are many unknowns about the likely risks and benefits for people like them.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.

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2. MacCallum, C. A., Lo, L. A., Pistawka, C. A., Christiansen, A., & Boivin, M. (2024). Cannabis vaporisation: Understanding products, devices and risks. Drug and Alcohol Review, 43(3), 732–745. https://doi.org/10.1111/dar.13800
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7. (American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders. Text revision.)
8. World Health Organization. (2016). The health and social effects of nonmedical cannabis use.
9. Fogel, J. S., Kelly, T. H., Westgate, P. M., & Lile, J. A. (2017). Sex differences in the subjective effects of oral Δ9-THC in cannabis users. Pharmacology Biochemistry and Behavior, 152, 44–51. https://doi.org/10.1016/j.pbb.2016.01.007
10. Haleem, R., & Wright, R. (2020). A Scoping Review on Clinical Trials of Pain Reduction With Cannabis Administration in Adults. Journal Of Clinical Medicine Research, 12(6), 344-351.
11. Sawtelle, L., & Holle, L. M. (2021). Use of Cannabis and Cannabinoids in Patients With Cancer. Annals of Pharmacotherapy, 55(7), 870–890. https://doi.org/10.1177/1060028020965224
12. Nelson, K. M., Bisson, J., Singh, G., Graham, J. G., Chen, S.-N., Friesen, J. B., Dahlin, J. L., Niemitz, M., Walters, M. A., & Pauli, G. F. (2020). The Essential Medicinal Chemistry of Cannabidiol (CBD). Journal of Medicinal Chemistry, 63(21), 12137–12155. https://doi.org/10.1021/acs.jmedchem.0c00724
13. Sarris, J., Sinclair, J., Karamacoska, D., Davidson, M., & Firth, J. (2020). Medicinal cannabis for psychiatric disorders: A clinically-focused systematic review. BMC Psychiatry, 20(1), 24. https://doi.org/10.1186/s12888-019-2409-8
14. Nguyen, N., Wong, M., Delucchi, K., & Halpern-Felsher, B. (2022). Adolescents’ and young adults’ perceptions of risks and benefits differ by type of cannabis products. Addictive Behaviors, 131, 107336. https://doi.org/10.1016/j.addbeh.2022.107336
15. Goodman, S., & Hammond, D. (2022). Perceptions of the health risks of cannabis: Estimates from national surveys in Canada and the United States, 2018–2019. Health Education Research, 37(2), 61–78. https://doi.org/10.1093/her/cyac006
16. Stall, N. M., Shi, S., Malikov, K., Wang, S., Rochon, P. A., Hillmer, M. P., & Zipursky, J. S. (2024). Edible Cannabis Legalization and Cannabis Poisonings in Older Adults. JAMA Internal Medicine, 184(7), 840. https://doi.org/10.1001/jamainternmed.2024.1331
17. MacCallum, C. A., Lo, L. A., Pistawka, C. A., & Boivin, M. (2023). A Clinical Framework for Evaluating Cannabis Product Quality and Safety. Cannabis and Cannabinoid Research, 8(3), 567–574. https://doi.org/10.1089/can.2021.0137

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