Fasting - Warfarin Sodium Interaction Details

There are multiple interactions reported between these two agents.

Interaction Details

Warfarin Sodium is classified as belonging to the following category: Anticoagulant/Antiplatelet Drugs

Fasting may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Fasting has been found to increase the international normalized ratio (INR) in patients stabilized on warfarin. Closely monitor patients who are fasting while taking anticoagulant or antiplatelet drugs. Dose adjustment may be necessary.

Interaction Rating

Moderate

Likelihood of Occurrence

Possible

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists

References

Wilhelmi de Toledo F, Grundler F, Bergouignan A, Drinda S, Michalsen A. Safety, health improvement and well-being during a 4 to 21-day fasting period in an observational study including 1422 subjects. PLoS One. 2019;14(1):e0209353.
Katada Y, Nakagawa S, Nishimura A, et al. Effects of fasting on warfarin sensitivity index in patients undergoing cardiovascular surgery. Eur J Clin Pharmacol. 2019;75(4):561-568.
Lai YF, Cheen MHH, Lim SH, et al. The effects of fasting in Muslim patients taking warfarin. J Thromb Haemost. 2014;12(3):349-54.

Interaction Details

Warfarin Sodium is classified as belonging to the following category: Warfarin (Coumadin)

Theoretically, fasting may increase the risk of bleeding if used with warfarin.
Both postoperative fasting and Ramadan fasting have been found to increase the INR in patients previously stabilized on warfarin. Closely monitor patients who are fasting while taking warfarin. Dose adjustment may be necessary.

Interaction Rating

Major

Likelihood of Occurrence

Probable

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.

References

Katada Y, Nakagawa S, Nishimura A, et al. Effects of fasting on warfarin sensitivity index in patients undergoing cardiovascular surgery. Eur J Clin Pharmacol. 2019;75(4):561-568.
Lai YF, Cheen MHH, Lim SH, et al. The effects of fasting in Muslim patients taking warfarin. J Thromb Haemost. 2014;12(3):349-54.

Warfarin Sodium Overview

Warfarin is used to prevent blood clots from forming or growing larger in your blood and blood vessels. It is prescribed for people with certain types of irregular heartbeat, people with prosthetic (replacement or mechanical) heart valves, and people who have suffered a heart attack. Warfarin is also used to treat or prevent venous thrombosis (swelling and blood clot in a vein) and pulmonary embolism (a blood clot in the lung). Warfarin is in a class of medications called anticoagulants ('blood thinners'). It works by decreasing the clotting ability of the blood.

See More Information Regarding Warfarin

Fasting - More Interactions

Fasting interacts with 204 drugs

Interaction Rating Key

These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.

Major	The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur.
Moderate	Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur.
Minor	Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction.
Unknown	No interactions have been reported or no interaction data is currently available.