Cannabidiol (CBD), the main non-intoxicating compound in cannabis, has been hypothesized to reduce the adverse effects of Δ9-tetrahydrocannabinol (THC), the primary psychoactive and analgesic component of cannabis. But does CBD improve the tolerability of THC as an analgesic?

We investigated this question in a randomized, double-blind, placebo-controlled clinical trial conducted in collaboration with researchers from the Centre for Human Drug Research, Leiden, The Netherlands. The study involved 37 healthy volunteers who received either a placebo, THC 9 mg alone, or THC 9 mg combined with CBD at doses of 10 mg (about 1:1 THC to CBD), 30 mg (1:3), or 450 mg (1:50). Psychoactive, psychomotor, cognitive, and analgesic effects were assessed using standardized test batteries.

The study found that 450 mg of CBD significantly increased THC’s subjective effects, including a 60.5% increase in “Feeling High,” compared to THC alone. CBD at lower doses (10 mg and 30 mg) had no significant effect on THC’s adverse or analgesic effects. Pharmacokinetic analyses showed that 450 mg CBD significantly increased THC and 11-OH-THC exposure, suggesting a pharmacological interaction.

These findings challenge the common idea that CBD reduces THC’s adverse effects or enhances its tolerability. The article, titled “Cannabidiol Does Not Reduce Δ9-Tetrahydrocannabinol Adverse Effects or Enhance Analgesia: A Randomized Trial,” was recently published in the peer-reviewed journal Clinical pharmacology and therapeutics.

Read the full article here: https://pubmed.ncbi.nlm.nih.gov/39054656/.