VENLAFAXINE AND WARFARIN AND OTHER ORAL ANTICOAGULANTS

There are a handful of isolated case reports indicating that the effects of warfarin are occasionally increased by venlafaxine. These reports describe increased prothrombin times, raised INRs and bleeding (haematuria, gastrointestinal bleeding, melaena, haemarthrosis).
It would seem prudent to increase INR monitoring if venlafaxine is added or withdrawn from treatment with warfarin.