Cannabinoids and COVID-19: Promising Signals, but No Proven Prevention or Long-COVID Treatment
A 2023 scoping review from researchers at Dalhousie University examined whether cannabinoids and the body’s endocannabinoid system might influence COVID-19 before, during, or after infection. The review, published in the Journal of Clinical Medicine, identified possible antiviral, anti-inflammatory, and symptom-management effects—but it did not establish cannabis as a proven way to prevent COVID-19, treat the infection, or resolve Long COVID.
The authors reviewed research suggesting that cannabinoid compounds may affect several processes involved in SARS-CoV-2 infection. In laboratory and preclinical studies, some cannabinoids appeared to interfere with viral entry into cells, reduce oxidative stress, or moderate inflammatory responses associated with severe disease. These mechanisms provide possible directions for drug development, but findings from cell cultures, animal models, and studies of other diseases cannot be assumed to predict benefits in people with COVID-19.
The review also discussed cannabinoids as a possible way to manage symptoms that can occur after infection, including anxiety, depression, post-traumatic stress symptoms, insomnia, pain, and reduced appetite. That evidence largely comes from research into cannabinoid-based treatments for those symptoms in other medical contexts. The review did not demonstrate that cannabis or CBD treats the underlying causes of Long COVID.
Some separate studies have produced intriguing findings. A 2022 laboratory study from Oregon State University and Oregon Health & Science University found that the cannabinoid acids CBDA and CBGA blocked SARS-CoV-2 from entering human cells in cell-based experiments. The compounds are acidic precursors to CBD and CBG, and the researchers tested purified substances—not marijuana smoking or ordinary cannabis products. The full study therefore offers a laboratory lead, not evidence that cannabis consumption prevents infection.
Observational hospital studies have also reported associations between cannabis use and less severe outcomes among some hospitalized COVID-19 patients. For example, a retrospective cohort study of 1,831 patients found that current cannabis use was associated with lower disease severity and reduced need for intensive care or mechanical ventilation after statistical adjustment. However, such studies cannot prove that cannabis caused the better outcomes. Differences in patients’ health, behavior, access to care, medication use, or patterns of cannabis consumption may have influenced the results. The study’s authors called for further research rather than clinical adoption.
The Dalhousie review emphasized similar limitations. Cannabis products vary widely in their cannabinoid concentrations, formulations, and routes of administration. Effects may also differ by age, dose, medical history, and whether a product contains THC. In addition, much of the evidence cited by the review came from research unrelated to SARS-CoV-2. Translating those findings into a safe and effective COVID-19 treatment would require carefully controlled clinical trials.
These distinctions are important because laboratory compounds are not interchangeable with smoked cannabis, edibles, CBD products, or prescription cannabinoid medicines. Heating can chemically change cannabinoid acids, while commercial products may contain inconsistent amounts of active ingredients. Cannabis use can also cause adverse effects and interact with medications, making self-treatment particularly risky for people who are ill or taking other drugs.
For prevention, the Centers for Disease Control and Prevention identifies COVID-19 vaccination as the best available tool for reducing the risk of Long COVID and recommends prompt evaluation for testing and treatment when people at higher risk develop symptoms. Current clinical care for Long COVID focuses on assessing individual symptoms, treating related conditions, and improving function and quality of life. The CDC’s clinical guidance does not recommend cannabinoids as an established treatment.
Overall, the Dalhousie review supports continued investigation of specific cannabinoid compounds and the endocannabinoid system. It does not show that cannabis prevents COVID-19 or treats Long COVID, and it should not be interpreted as a reason to replace vaccination, antiviral treatment, or medical care with cannabis products. Clinical trials will be needed to determine whether any cannabinoid-based therapy is effective, which compound and dose might be appropriate, and how its risks compare with existing treatments.
