Fluconazole and Warfarin

A January 2006 Obstetrics and Gynecology article highlighted Fluconazole (brand name Diflucan®) as an interactive medication impacting warfarin patients.

The study evaluated the impact on prothrombin time among 6 women who were long-term warfarin users. The women all had an INR target range between 2.0-3.0. Patient INRs were stable after two consecutive INR values were obtained.

The investigators evaluated a single dose of oral 150-milligram dose of fluconazole on stable INR test results. INR tests were performed on day 2, 5 and 8 following the 150 milligrams of fluconazole.

The increase in INR was 11% day 2, 34% day 5 and 2% day 8 off of baseline INR measures. The differences were not statistically significant, however half of the women had a clinically relevant increase in INR above 4 or bleeding requiring a dosage reduction.1

The authors concluded: "A single 150-mg oral dose of fluconazole may increase the PT to a clinically relevant level in a woman on chronic warfarin therapy. Clinicians should monitor the PT carefully after a single dose of fluconazole."1

As with all medications, please consult your doctor before taking any medications as they may interact with warfarin.

  1. Turrentine MA. Single-dose flucoazole for vulvovaginal candidiasis: impact on prothrombin time in women taking warfarin. Obstetrics and Gynecology. February 2006: 107(2 pt 1): 310-3.