The introduction of the direct oral anticoagulants (DOACs) has led to their widespread use for stroke prevention and venous thromboembolism, but little is known about the numbers of patients switching from a DOAC to (or back to) a warfarin or the reasons for doing so. This study was an analysis of prospectively collected data from a 4-year period surveying a warfarin dose adjustment clinic in a large city centre hospital with the primary objective to identify these reasons. In our clinic with 1791 patients annually under review, 40 patients were identified as having switched from a DOAC to warfarin with the most common reasons for switching being bleeding, re-thrombosis and renal deterioration. Other reasons included medication interactions, side effects, antiphospholipid syndrome, valvular replacement or arterial embolism. Clinical events following warfarin commencement were also recorded. Overall, these data suggest that switching from a DOAC to warfarin is seldom deemed necessary by clinicians. However, as the number of patients receiving DOACs continues to increase, it is vital that health care professionals remain vigilant regarding medication interactions, bleeding risk and changing renal function.

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