The jury is still out on the effectiveness of CBD as a treatment for Covid-19 following a review of published research papers.
German academics who analysed nine papers published between September and December 2020 found CBD to be a promising anti-inflammatory agent for severely infected patients, but said more clinical studies are needed.
Of the nine papers, five were in vivo studies and three were in vitro studies using human tissues.
None of the animal models had Covid-19, but they were used to determine the effect of CBD on acute lung inflammation or injury, asthma, and acute respiratory distress syndrome (ARDS).
CBD was reported to decrease multiple inflammatory cytokines and reduce ARDS symptoms.
In the in vitro human tissue models, CBD treatment was associated with a lower expression of A2A receptors and reduced inflammation.
A single human randomised clinical trial of CBD treatment in patients with mild to moderate Covid-19 found no significant improvement for CBD as compared to controls for the prevention of severe disease, reduced symptom duration, lower cytokine levels, reduced lung damage, hospitalisation, or mortality.
A single open-label trial reported reduced burnout and emotional fatigue among frontline Covid-19 workers following treatment with CBD. However, 10% of participants reported serious adverse events, although all made a full recovery.
The authors conclude: “CBD has shown some promising anti-inflammatory effects in a few pre-clinical studies, but not in the few human studies. Evidence on beneficial or harmful effects of CBD in the treatment of Covid-19 is missing and should be further investigated.”