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
Drug	Effect	Intervention
Warfarin	THC 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
Clopidogrel	CBD and possibly THC can increase clopidogrel level due to the competitive inhibition of CYP2C19.	Consider using another antiplatelet
Heparin/fondaparinux	No known interactions as these agents are processed by endothelial and renal cells and not metabolized by CYP enzymes, UGT, or P-glycoprotein.
Platelets	Immune thrombocytopenia with synthetic cannabis.	Unlikely to have significant clinical effects Immune thrombocytopenia is rare