MAJOR — Use With Caution
FDA-documented interaction. INR monitoring recommended when starting or stopping ciprofloxacin in warfarin patients.
Evidence level: STRONG
Ciprofloxacin (Cipro) can increase warfarin blood-thinning effect, raising your bleeding risk. It interferes with how your body breaks down warfarin and may also reduce vitamin K from gut bacteria.
Ciprofloxacin inhibits CYP1A2 and possibly CYP3A4, affecting warfarin R-enantiomer metabolism. Also may affect vitamin K-producing gut flora. FDA warfarin label lists fluoroquinolones as potentiating anticoagulant effect.
Get your INR checked within 3-5 days of starting Cipro. Report any unusual bleeding immediately. The effect may persist for several days after finishing the antibiotic.
Space Warfarin at least 2 hours from Ciprofloxacin. Follow antibiotic-specific food instructions carefully. Complete the full antibiotic course even if symptoms improve.
Higher risk for: elderly patients, those with liver disease, history of GI bleeding, concurrent use of multiple blood thinners, recent surgery, vitamin K intake changes, alcohol use, or low body weight.
Unusual bruising, bleeding gums, blood in urine or stool, prolonged bleeding from cuts
Request INR monitoring. Ask if an alternative antibiotic with less warfarin interaction potential could be used.
This medication combination requires careful medical oversight. Your doctor or anticoagulation clinic can adjust doses or select alternatives with fewer bleeding risks. Frequent INR monitoring is essential.
Ciprofloxacin (Cipro) can increase warfarin blood-thinning effect, raising your bleeding risk. It interferes with how your body breaks down warfarin and may also reduce vitamin K from gut bacteria.
Space Warfarin at least 2 hours from Ciprofloxacin. Follow antibiotic-specific food instructions carefully. Complete the full antibiotic course even if symptoms improve.
Unusual bruising, bleeding gums, blood in urine or stool, prolonged bleeding from cuts
This medication combination requires careful medical oversight. Your doctor or anticoagulation clinic can adjust doses or select alternatives with fewer bleeding risks. Frequent INR monitoring is essential.
Request INR monitoring. Ask if an alternative antibiotic with less warfarin interaction potential could be used.
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