Dicloxacillin and Warfarin

Dicloxacillin is a penicillin-like antibiotic used to treat certain infections. Patients receiving dicloxacillin are likely to see an effect on their INR test values. Patients taking dicloxacillin for more than a week may benefit from more frequent INR testing as a lower INR test result is possible.1

Unlike many antibiotics, which can increase the intensity of warfarin, dicloxacillin products decrease it.2 As always, please consult with your doctor before taking medications, as it may interact with warfarin.

  1. Mailloux AT, Gidal BE, Sorkness CA. Potential interaction between warfarin and dicloxacillin. Ann Pharmacother. 1996 Dec;30(12):1402-7.
  2. Lacey CS. Interaction of dicloxacillin with warfarin. Ann Pharmacother. 2004 May; 38(5):898. Epub 2004 Mar 30.