The public interest in whether cannabis can help with COVID-19 stems from the plant’s complex chemical profile, which contains hundreds of compounds known as cannabinoids. Research has primarily focused on the non-psychoactive cannabidiol (CBD) and the intoxicating delta-9-tetrahydrocannabinol (THC), along with their acidic precursors. Scientists are investigating the potential of these compounds as both an early-stage prophylactic agent and a treatment for the severe inflammatory response caused by the SARS-CoV-2 virus. However, most promising findings remain confined to laboratory and animal models, without clinical recommendations for human use.
Cannabinoids and Preventing Viral Entry
Early laboratory studies have identified specific, non-intoxicating cannabinoid acids that could potentially interfere with the SARS-CoV-2 infection process. Cannabigerolic acid (CBGA) and cannabidiolic acid (CBDA) have shown an ability to bind to the virus’s spike protein in in vitro settings using human epithelial cells. This binding action theoretically changes the spike protein’s shape, preventing the virus from attaching to the human angiotensin-converting enzyme 2 (ACE2) receptor, the primary gateway for cell entry.
These initial findings were demonstrated using purified compounds and were effective against some early variants of concern, such as the Alpha and Beta variants. The research suggests that a cell entry inhibitor could be a viable antiviral strategy to prevent infection or shorten the course of the disease. CBGA and CBDA are raw compounds found in the hemp plant, not the more common CBD and CBG products created after heat exposure.
Other studies have explored a different mechanism where cannabidiol (CBD) may inhibit viral replication after the virus has already entered the host cell. In human lung cells and mouse models, high-purity CBD was found to block the virus from making copies of itself by activating the host cell’s antiviral response. This indicates that different cannabinoids may act at distinct phases of the infection cycle, offering separate avenues for therapeutic investigation.
The Role of Cannabis Compounds in Controlling Inflammation
A second major area of focus is the potential of cannabinoids to mitigate the severe immune overreaction that characterizes serious COVID-19 cases. In some patients, the immune system responds to the virus with an uncontrolled release of pro-inflammatory signaling molecules called cytokines, commonly referred to as a “cytokine storm.” This excessive inflammation can lead to Acute Respiratory Distress Syndrome (ARDS) and widespread lung damage.
Cannabidiol (CBD) has demonstrated potent anti-inflammatory and immunomodulatory effects in preclinical models. Studies using mouse models of ARDS, which simulate the lung inflammation seen in severe COVID-19, showed that administering CBD significantly reduced the levels of pro-inflammatory cytokines, such as IL-6 and TNF-alpha. This downregulation of the immune response helped the lungs recover and improved blood oxygen levels.
Researchers suggest that CBD may help restore inflammatory balance by interacting with the body’s endocannabinoid system and other molecular pathways. The goal of this research is not to treat the initial infection but to manage the subsequent systemic hyper-inflammation that causes serious illness and death. These findings highlight the potential for specific cannabinoids to act as a supportive therapy in the later stages of severe infection.
Respiratory Risks and Potential Drug Interactions
Inhaling cannabis smoke or vapor presents direct pulmonary risks, which is particularly concerning in the context of a respiratory disease like COVID-19. Smoking cannabis can damage lung tissues and impair the function of cilia, the small hair-like structures that help clear the respiratory tract of pathogens and debris. This compromised respiratory function may increase susceptibility to infection and worsen symptoms, making complications like pneumonia more likely.
Studies have shown that people who use cannabis or nicotine products via smoking or vaping report a higher frequency of self-reported COVID-19 symptoms and dyspnea, or difficulty breathing. Furthermore, some research indicates that the elevated risk of severe COVID-19 outcomes, including hospitalization and intensive care admission, for cannabis users is comparable to that observed in tobacco smokers. These risks apply to both smoking and vaping.
Beyond respiratory issues, cannabinoids like CBD and THC can cause dangerous interactions with other medications by affecting the body’s metabolic system. Both compounds are metabolized by a group of liver enzymes known as the cytochrome P450 (CYP450) family, particularly the CYP3A4 enzyme. CBD and THC can inhibit these enzymes, which may lead to dangerously high or low concentrations of other drugs that are metabolized by the same pathway. Many common COVID-19 treatments rely on the CYP450 system, necessitating caution when combining them with cannabis.
Current Scientific Consensus and Future Research
Despite the promising mechanisms identified in laboratory and animal studies, the current scientific consensus is that there is no clinical evidence to support the use of cannabis or its compounds for the prevention or treatment of COVID-19. Major regulatory bodies, such as the U.S. Food and Drug Administration (FDA), have not approved or authorized any cannabis-derived drug for this purpose. The FDA has issued multiple warning letters to companies that misleadingly marketed CBD products with claims they could cure, treat, or prevent COVID-19.
The encouraging results from preclinical work on viral entry inhibition and inflammation control must be validated in large-scale, randomized, controlled human trials. Researchers caution that the beneficial effects seen in the lab often involve high-purity, specially formulated doses not found in over-the-counter commercial cannabis products. Future research is focused on determining optimal dosages, timing, and delivery methods for isolated cannabinoids to maximize potential benefits while minimizing side effects.