Table 2

Cannabinoid drug Interactions with anticoagulants and antiplatelets used with permission from Samer Narouze, MD, PhD 60–62

Cannabinoids drug interactions with anticoagulants and antiplatelets
WarfarinTHC and CBD can cause competitive inhibition of CYP2C9 and inhibit metabolism of the S-warfarin isomer, leading to supratherapeutic international normalized ratio levels.
  • Check INR within 3 days

DOACs (direct-acting oral anticoagulants)CBD and possibly THC can increase DOACs level due to competitive inhibition of P-glycoproteins, and to a lesser extent CYP3A4.
  • Close monitoring

  • Consider using other anticoagulants or discontinue CBD/THC

ClopidogrelCBD and possibly THC can increase clopidogrel level due to the competitive inhibition of CYP2C19.
  • Consider using another antiplatelet

Heparin/fondaparinuxNo known interactions as these agents are processed by endothelial and renal cells and not metabolized by CYP enzymes, UGT, or P-glycoprotein.
PlateletsImmune thrombocytopenia with synthetic cannabis.
  • Unlikely to have significant clinical effects

  • Immune thrombocytopenia is rare

  • CBD, cannabidiol; THC, tetrahydrocannabinol.