WHICH: RISKS OF MEDICINAL CANNABIS
Learn more about the risks and side effects that are associated with medicinal cannabis.
What are the side effects of medicinal cannabis?
Medicinal cannabis can have different effects on different people, depending on the patient’s body, the type of product, and how it is being consumed. Some patients could experience one or more side effects associated with the use of medicinal cannabis, although they are most often mild to moderate, and temporary. Some more common side effects include1,2:
- dry mouth
This is not a complete list of all potential side effects from medicinal cannabis. In addition, there are also potential risks to the lungs if cannabis is inhaled, and potential risks to the skin if cannabis is applied topically, including contact dermatitis.
Will a patient’s side effects due to medicinal cannabis change over time?
The side effects associated with medicinal cannabis could be reduced over time. This does not happen with all patients. This effect is called tolerance. You should reach out to your physician for a recommendation and advice about possible side effects affecting your concrete medical condition.1,3
Are there people who should not take medicinal cannabis?
Yes. There are several patient groups that should not take medicinal cannabis. This includes1,3,4:
- patients with a known allergy or hypersensitivity to cannabinoids
- patients that are less than 18 years old
- patients with severe cardiovascular disease
- women that are pregnant or breastfeeding
- patients with a personal history of mental disease
- patients with pulmonary disease (for inhaled use)
What are the risks of medicinal cannabis for children?
Cannabinoids can influence many parts of the brain, including those that are responsible for learning and memory. Since these areas are still developing in younger brains, exposure to cannabinoids could lead to short-term memory impairment. Frequent use of medicinal cannabis in patients under the age of 18 could result in some cognitive problems. Medicinal cannabis is contraindicated in patients that are less than 18 years old. Therefore, use in younger patients should be carefully assessed and should consider the benefits and risks.1,3,4
What are the risks of medicinal cannabis if a patient is pregnant or breastfeeding?
Cannabinoids have been shown to pass the placental barrier in pregnant women, which means that they can reach the fetus and affect development. Cannabinoids can also pass via breast milk and affect development in infants. Medicinal cannabis is contraindicated in pregnant women and women that are breastfeeding.1,3,4
What are the risks of medicinal cannabis for family planning?
Several studies have determined that cannabinoids can interact with reproductive hormones in men and women, and that they can lead to a decrease in sperm count, concentration, and motility. If a patient or their partner are trying to get pregnant, they should consult with their physician about the benefits and risks of taking medicinal cannabis.3,5
What are the risks of medicinal cannabis for older patients?
Older patients may be more sensitive to cannabinoids, especially if they have kidney or liver problems. These patients should discuss their specific situation with a physician. Their physician may consider a lower starting dose of medicinal cannabis for such patients.3,4
What should a patient do if they have side effects from taking medicinal cannabis?
If a patient experiences side effects, they should seek advice from their physician or pharmacist.
Can a patient overdose from taking too much medicinal cannabis?
The symptoms associated with an intoxication by cannabis may include depression, anxiety, panicking, faints, impaired motor coordination, lethargy, and changes in the cardiac rhythm. In general, these symptoms disappear in a few hours.3
Can a patient become addicted to medicinal cannabis?
Medicinal cannabis containing THC can produce both psychological and physical dependence, however not all patients who use medicinal cannabis develop dependence. If a patient uses medicinal cannabis frequently (every day) and for a long period of time (months or years), they may have difficulty stopping it on their own. If a patient needs to stop their medicinal cannabis, they will be instructed by their physician to down-titrate their dose slowly and therefore mitigate any withdrawal effect.3,6
Patients who frequently use medicinal cannabis report withdrawal symptoms when stopping abruptly. Such symptoms could include irritability, trouble sleeping, decreased appetite, cravings, restlessness, and/or various forms of physical discomfort. These symptoms usually appear within the first 1 to 2 days following discontinuation and should resolve within 1 to 2 weeks.3,6
- MacCallum CA, Russo EB. Practical considerations in medical cannabis administration and dosing. Eur J Intern Med. 2018 Mar;49: 12-9.
- Barnes M, Barnes J. Cannabis: the evidence for medical use. London: All-Party Parliamentary Group for Drug Policy Reform. May 2016.
- Health Canada. Information for Health Care Professionals: Cannabis and the cannabinoids. October 2018. ISBN: 978-0-660-27828-5.
- Häuser W, Finn DP, Kalso E, et al. European Pain Federation (EFIC) position paper on appropriate use of cannabis-based medicines and medical cannabis for chronic pain management. Eur J Pain. 2018 Oct;22(9): 1547-64.
- Jordan T, Ngo B, Jones CA. The use of cannabis and perceptions of its effect on fertility among infertility patients. Hum Reprod Open. 2020 Feb;2020(1): hoz041.
- Lichtman AH, Martin BR. Cannabinoid tolerance and dependence. Handb Exp Pharmacol. 2005;(168): 691-717.