Oral Corticosteroids & Warfarin

Corticosteroids are used to treat a variety of problems, including arthritis, asthma, skin conditions such as eczema and rashes, and autoimmune diseases such as lupus and multiple sclerosis. These steroids are similar to hormones that your adrenal glands produce to fight stress that is normally associated with illness and injuries. According to the National Institutes of Health, steroids can have strong side effects, including weakening of the bones and cataracts.

Interaction with warfarin?

A study published in the Annals of Pharmacotherapy found oral corticosteroids may interact with warfarin, but the documentation was limited. The study limitations included a lack of standardization of testing frequency.1

29 of the 32 (90%) patients experienced an increase in INR test results. Only 2 patients experienced a decrease in INR values during the study. The average increase was 1.24 (95% CI 0.86 to 1.62). The average INR change was seen 6.7 days after the first corticosteroid exposure. Half the patients experiencing an increase in test results required a change in their warfarin dosing. None of the study patients required hospitalization.1

Increasing testing frequency is recommended when starting or stopping any new medication or dietary supplement including vitamins. Home INR monitoring will help improve your control of warfarin. More frequent testing, typically performed by patient self testing, is a valuable tool for detecting rises and falls in INR values and enable you to work with your clinician to make any adjustments to diet or medication dosing.2 Go to the Getting Started page for more information about testing your INR at home.

  1. Hazlewood, Kathleen A., Fugate Susan E., Harrison Donald L. Effect of Oral Corticosteroids on Chronic Warfarin Therapy. Ann Pharmacother December 2006 vol. 40 no. 12 2101-2106.
  2. Center for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management (CAG-00087R) [Memorandum]. 2008. Baltimore, MD.