Study: CBD May Increase THC Levels in Blood When Cannabis Is Vaporized, Research Finds
- CBD combined with THC significantly increases THC levels in the bloodstream, with total THC exposure rising by about 75% and peak THC levels nearly doubling compared to THC alone.
- The study used a randomized, double-blind, placebo-controlled design with 48 participants aged 16–17 and 26–29, examining blood samples after inhaling THC alone, THC+CBD, or placebo.
- Findings suggest that CBD may enhance THC absorption or alter its metabolism even when both are inhaled, not just when consumed orally, with similar effects observed in both adolescents and adults.
- The research adds to evidence that CBD is not pharmacologically neutral alongside THC, potentially influencing THC’s potency and duration, though further studies are needed due to mixed prior results.
A study published in Drug and Alcohol Dependence reports that cannabidiol (CBD) may increase the amount of THC circulating in the bloodstream when the two are inhaled together, potentially altering how cannabis affects users.
The study was conducted by researchers from King’s College London and University College London, and examined how CBD influences the pharmacokinetics of THC when cannabis is vaporized and inhaled.
Researchers used a randomized, double-blind, placebo-controlled design involving 48 participants split between adolescents (16–17) and adults (26–29). Participants were given three different cannabis conditions: THC alone, THC combined with CBD, and a placebo. Blood samples were collected before use and at multiple intervals afterward to measure THC and its metabolites.
The findings showed that combining CBD with THC led to significantly higher levels of THC in the bloodstream compared to THC alone. Specifically, total THC exposure increased by roughly 75%, while peak THC levels were nearly doubled in the THC+CBD condition.
The study also found increases in THC metabolites, although some of these changes were not statistically significant. Researchers say the results indicate that CBD may enhance THC absorption or alter how the body processes it, even when both are inhaled rather than consumed orally.
Notably, the analysis found no strong evidence that these effects differed between adolescents and adults, suggesting similar pharmacokinetic responses across age groups.
Researchers note that prior studies on this topic have produced mixed results, meaning more research is needed to fully understand the interaction. However, the findings add to growing evidence that CBD is not pharmacologically neutral when combined with THC, and may influence both its potency and duration in the body.