12 Cannabinoids Tested Against 6 Liver Enzymes: CBD and THC Were the Strongest Inhibitors

This was the most comprehensive cannabinoid-enzyme interaction study published to date. Researchers tested 12 different cannabinoids — including THC, CBD, CBN, CBG, CBC, THCV, and others — against 6 major drug-metabolizing CYP enzymes (CYP3A4, CYP2D6, CYP2C9, CYP1A2, CYP2B6, CYP2C19).

CBD emerged as the most potent inhibitor across multiple enzymes, consistent with previous reports. THC was also a significant inhibitor, particularly of CYP1A2 and CYP2C9. But the study's novel contribution was showing that so-called "minor" cannabinoids — CBN, CBG, and others present in full-spectrum cannabis products — also inhibited these enzymes at relevant concentrations.

This matters because full-spectrum cannabis products contain multiple cannabinoids simultaneously. The combined inhibitory load of several cannabinoids acting on the same enzymes could be greater than any single cannabinoid alone, creating unpredictable drug interactions.

Cannabis products are sold as isolates (pure CBD or THC) and as full-spectrum (containing multiple cannabinoids). This study showed that the full-spectrum products may carry additional drug interaction risk because minor cannabinoids also inhibit the same liver enzymes. Someone taking a full-spectrum CBD oil is exposed to a cocktail of enzyme inhibitors, not just one.

For the growing population of medical cannabis patients who are also on prescription medications — often multiple — this is clinically significant information that rarely appears on product labels.