Drug interactions
Cefazolin + Warfarin
Severity: Moderate
Cefazolin and Warfarin: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Cephalosporins, including cefazolin, have been reported to increase INR in patients taking warfarin, occasionally with bleeding. Infection, poor intake and antibiotic effects on gut flora may all contribute, so the size of the effect varies.
What this interaction means in plain words
Cefazolin and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Cefazolin belongs to Anti Bacterial; Warfarin belongs to Cardiovascular.
Why it happens
Probably reduced vitamin K availability from gut flora suppression, plus possible effects of the underlying illness; not firmly established.
What to do
Check INR within a few days of starting cefazolin and again after stopping it. Adjust the warfarin dose according to INR and watch for bleeding.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Cefazolin
- Amikacin + Cefazolin Moderate
- Bcg vaccine live + Cefazolin Moderate
- Cefazolin + Cholera vaccine Moderate
- Cefazolin + Dexamethasone-tobramycin Moderate
- Cefazolin + Gentamicin Moderate
- Cefazolin + Kanamycin Moderate
Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Frequently asked questions
Can I take Cefazolin with Warfarin?
MediHelp rates the interaction as moderate. Cefazolin and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Cephalosporins, including cefazolin, have been reported to increase INR in patients taking warfarin, occasionally with bleeding. Infection, poor intake and antibiotic effects on gut flora may all contribute, so the size of the effect varies.
How serious is the interaction between Cefazolin and Warfarin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR within a few days of starting cefazolin and again after stopping it. Adjust the warfarin dose according to INR and watch for bleeding.
What other medicines interact with Cefazolin?
MediHelp also lists interactions of Cefazolin with, for example, Amikacin, Bcg vaccine live, Cholera vaccine. The full list is on the Cefazolin page.
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