Medical cannabis and cannabinoids in raw or dried flowers, oils, capsules, powders, edibles, and topicals may reduce pain, and some evidence shows benefit with nausea, vomiting, and sleep, but little evidence of improving treatment outcomes.
Safety and precautions
We advise medical supervision and monitoring when using cannabis for medical purposes. Cannabis can impair driving and other tasks requiring judgment and rapid response, so caution is warranted.
Cancer promotion
Side effects or adverse events
Interactions with cancer treatments
Cardiovascular health effects
Smoking cannabis carries many of the same cardiovascular health hazards as smoking tobacco. While the level of evidence is modest, enough data has accumulated to advise caution in using cannabis for people at highest risk of cardiovascular events, including those who present with a heart attack or new arrhythmia, or who have been hospitalized with heart failure.11DeFilippis EM, Bajaj NS et al. Marijuana use in patients with cardiovascular disease: JACC Review Topic of the Week. Journal of the American College of Cardiology. 2020 Jan 28; 75(3):320-332; American College of Cardiology. Potential link between marijuana and heart risks discovered by cardiologists. SciTechDaily. January 20, 2020. Viewed October 9, 2021.
THC in cannabis is associated with endothelial dysfunction (a type of non-obstructive coronary artery disease).12Page RL 2nd, Allen LA et al. Medical marijuana, recreational cannabis, and cardiovascular health: a scientific statement from the American Heart Association. Circulation. 2020;CIR0000000000000883.
Other side effects
THC in cannabis can have these effects:13Page RL 2nd, Allen LA et al. Medical marijuana, recreational cannabis, and cardiovascular health: a scientific statement from the American Heart Association. Circulation. 2020;CIR0000000000000883.
- Sympathetic nervous system (“fight or flight”) stimulation, which increases heart rate, myocardial oxygen demand, blood pressure, and platelet activation
- Parasympathetic nervous system (“rest and digest”) inhibition
- Associated with endothelial dysfunction (a type of non-obstructive coronary artery disease) and oxidative stress
- Higher risk of psychosis with use of high potency (high TCH) products compared to low-potency14Petrilli K, Ofori S et al. Association of cannabis potency with mental ill health and addiction: a systematic review. Lancet Psychiatry. 2022 Jul 25:S2215-0366(22)00161-4.
People treated with THC for pain withdrew from treatment due to adverse side effects more often than controls, with a higher likelihood of withdrawal among people treated with THC extracted from cannabis compared to synthetic THC in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 5 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects.15McDonagh MS, Morasco BJ et al. Cannabis-based products for chronic pain: a systematic review. Annals of Internal Medicine. 2022 Jun 7.
According to CAM-Cancer, “A number of adverse events have been observed after the intake of medical cannabis and cannabinoids. Some may be welcome, such as mood enhancement or sedation.”16Horneber M, Landwehr C, Kalbermatten Magaya N, Ritter C, Ziemann C. Medical cannabis and cannabinoids. CAM-Cancer. September 10, 2020. Viewed October 9, 2021. Side effects include these:
- Dry mouth
- Dizziness
- Sleepiness or drowsiness (somnolence)
- Fatigue or lack of energy (lethargy)
- Vomiting
- Fever
- Elevated liver values
Effects found in reviews of studies
Interactions with other therapies
CBD interacts with antiepileptic drugs, enhancing the serum levels of some and reducing the level of others.40Gaston TE, Bebin EM et al. Interactions between cannabidiol and commonly used antiepileptic drugs. Epilepsia. 2017 Sep;58(9):1586-1592.
Dependence and addiction
Using cannabis can lead to substance use disorders such as physical and/or psychological dependence in some people.41Wagener D. Marijuana Addiction Facts: Is Marijuana Physically Addictive? American Addiction Centers. August 26, 2021. Viewed October 9, 2021; National Institute on Drug Abuse. Marijuana Research Report: Is marijuana addictive? July 2020. Viewed October 9, 2021. Physical dependence on cannabis can develop with sustained use.42Grotenhermen F. Pharmacokinetics and pharmacodynamics of cannabinoids. Clinical Pharmacokinetics. 2003;42(4):327-60. High potency (high TCH) products are linked to a higher risk of cannabis use disorder compared to low-potency products.43Petrilli K, Ofori S et al. Association of cannabis potency with mental ill health and addiction: a systematic review. Lancet Psychiatry. 2022 Jul 25:S2215-0366(22)00161-4.
Regular cannabis users who wish to discontinue use should speak with a doctor for a medically supervised cessation plan.
CBD shows no indications for addiction or dependence in humans.44Expert Committee on Drug Dependence. News Briefing—40th WHO Expert Committee on Drug Dependence (ECDD). World Health Organization. September 13, 2018. Viewed October 9, 2021.
Resource
Continue exploring
References