Certain compounds isolated from the cannabis plant (Cannabis sativa L.) have shown a huge amount of potential as a treatment option for a variety of medical conditions. Current evidence demonstrates that formulations of these derivatives can be used in the treatment of chronic pain, epilepsy, chemotherapy-induced nausea and vomiting, and other medical conditions.
The main components of the cannabis plant that are studied for their medicinal properties are cannabidiol (CBD) and tetrahydrocannabinol (THC). These are both known as cannabinoids because their main effects are exerted through the human body’s own cannabinoid receptors.
In addition to established conditions where CBD has been shown to provide benefit to some patients, there are also a lot of claims made about its therapeutic properties with limited scientific evidence to support them. One such condition is viral infections. A recent systemic review published by scientists from the United Kingdom and Italy assessed the evidence that is currently available on CBD in viral illness and how this stacks up against the claims made across the internet.
What is the Current Evidence?
Studies were assessed for relevance based on the inclusion of the search terms ‘CBD’ and ‘viral’ or ‘virus’. Having assessed relevant studies, the researchers excluded reviews, duplicates, and studies of synthetic analogues, enriched extracts, or metabolites of CBD. Three studies were identified as relevant for review.
CBD and Hepatitis C Virus
One study assessed the effects of CBD on Hepatitis C (HCV) and Hepatitis B (HBV) viruses. The virus was assessed in a culture, over several days. It was discovered that CBD was able to inhibit the replication of HCV cells by up to 86.4%. These results were comparable to those of interferon-alpha (IFN-α) – a therapeutic drug that is currently used as a treatment for Hepatitis infections.
In addition, CBD was also found to be less cytotoxic (toxic to cells) than interferon-alpha. However, when compared to sofosbuvir, a Hepatitis C treatment drug, CBD was found to be less effective and more cytotoxic. CBD was also found to have no significant effect on the progression of the Hepatitis B Virus (HBV).
CBD and Kaposi’s Sarcoma-associated Herpesvirus
Another study assessed the effect of CBD on Kaposi’s sarcoma-associated herpesvirus (KSHV). The researchers used human dermal microvascular endothelial cells (HMVECs) to assess the progression of KHSV after treatment with CBD. The study showed that CBD had some indirect antiviral effects on KSHV.
Although CBD didn’t affect the efficiency with which KSHV infected the cells, it did appear to reduce the spread of KSHV-infected cells. CBD also limited restricted the development of KHSV-associated cancers in normal cells.
CBD and Theiler’s Murine Encephalomyelitis Virus
The final study assessed by the researchers analysed the effects of CBD on the effects of neuroinflammation induced by Theiler’s murine encephalomyelitis virus (TMEV) in mice. It was discovered that prolonged CBD exposure was able to decrease white blood cell infiltration and microglia activation in the brain of TMEV-infected mice.
As a result, CBD was able to improve motor symptoms and the neuroinflammation in the chronic phase of infection with TMEV. Although this study demonstrated that CBD has the potential to limit the impact of the chronic phase of the disease, restore motor function and reverse neuroinflammation, it did not provide any experimental evidence of direct or indirect antiviral effect of CBD.
The researchers also searched for anecdotal evidence from patients on the internet. Following a review of potentially relevant websites, 25 sources were deemed applicable to this research. Within these sources, CBD was described as beneficial in viral infections such as oral and genital herpes, common respiratory viruses, shingles, hepatitis C, HIV/AIDS, Ebola, and glandular fever.
The majority of these references were found on commercial websites, educational platforms, and online media. Although a large number of claims were made about the benefits of CBD for viral infections, few of these sources were supported by appropriate scientific research.
The Researchers’ Conclusions
The researchers concluded that CBD could potentially be considered as a novel targeted candidate for the treatment of hepatitis C and Kaposi’s Sarcoma. Also, this review supports the use of CBD as an anti-inflammatory treatment for the deleterious effects of neuroinflammation in TMEV-infected mice.
Although anecdotal evidence may suggest the potential of CBD to benefit some other viral infections, acceptable evidence is severely lacking. The researchers conclude that many of these claims were biased interpretations of current evidence and even dishonest manipulation by commercial retailers.
To conclude, the authors of the review stress that current findings and anecdotal evidence should be used to progress research into its applications in viral diseases and is not an appropriate treatment based on the limited evidence currently available.