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Drug class

Blood thinners (warfarin, direct-acting anticoagulants) and cannabis

Both CBD and THC can slow down the CYP2C9 and CYP3A4 liver enzymes that clear these drugs, so blood levels and INR can climb.

High risk

Why it happens

Both CBD and THC can slow down the CYP2C9 and CYP3A4 liver enzymes that clear these drugs, so blood levels and INR can climb.

What it means for you

Your bleeding risk can rise even though nobody changed your warfarin dose. INR readings may drift away from where they were.

What Tiffany advises

Tell your prescriber before you start cannabis. If you take warfarin, Tiffany suggests planning for more frequent INR checks during the first month.

Common examples

Generic names first, then brands.

  • warfarin
  • apixaban
  • rivaroxaban
  • dabigatran

Body systems involved

  • Bleeding
  • Heart and blood pressure

Take it further

Check this with my other meds

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Other classes at high risk

This page describes a drug class from aggregate published knowledge, reviewed by a pharmacist. Your own prescriber or pharmacist knows your doses and history; bring this page to that conversation.