What the FDA labels say about taking them together
Ciprofloxacin and warfarin
Ciprofloxacin's FDA label of March 2, 2026 names warfarin in its drug interactions section, and warfarin's label names ciprofloxacin too. The ciprofloxacin label: “Monitor prothrombin time and INR frequently during and shortly after co-administration of CIPRO with an oral anti-coagulant (for example, warfarin).”
Check it at the source: the ciprofloxacin FDA label on DailyMed (effective March 2, 2026, Bayer HealthCare Pharmaceuticals Inc.); the warfarin FDA label on DailyMed (effective May 29, 2026, Amneal Pharmaceuticals LLC).
What does the ciprofloxacin label say about warfarin?
Ciprofloxacin label, drug interactionsMonitor prothrombin time and INR frequently during and shortly after co-administration of CIPRO with an oral anti-coagulant (for example, warfarin).
Ciloxan label (Sandoz Inc, July 30, 2024), drug interactionsHowever, the systemic administration of some quinolones has been shown to elevate plasma concentrations of theophylline, interfere with the metabolism of caffeine, enhance the effects of the oral anticoagulant, warfarin, and its derivatives, and has been associated with transient elevations in serum creatinine in patients receiving cyclosporine concomitantly.
Source: FDA drug label (Ciloxan, NDA020369), Sandoz Inc, effective July 30, 2024 (SPL set 09ca5374-2a16-4a95-91b3-70591d78254e), via openFDA
Source: FDA drug label (Cipro), Bayer HealthCare Pharmaceuticals Inc., effective March 2, 2026 (SPL set 888dc7f9-ad9c-4c00-8d50-8ddfd9bd27c0), via openFDA; the full label on DailyMed
What does the warfarin label say about ciprofloxacin?
Warfarin label, drug interactionsClosely monitor INR if a concomitant drug is a CYP2C9, 1A2, and/or 3A4 inhibitor or inducer. Examples of CYP450 Interactions with Warfarin Enzyme Inhibitors Inducers CYP2C9 amiodarone, capecitabine, cotrimoxazole, etravirine, fluconazole, fluvastatin, fluvoxamine, metronidazole, miconazole, oxandrolone, sulfinpyrazone, tigecycline, voriconazole, zafirlukast aprepitant, bosentan, carbamazepine, phenobarbital, rifampin CYP1A2 acyclovir, allopurinol, caffeine, cimetidine, ciprofloxacin, disulfiram, enoxacin, famotidine, fluvoxamine, methoxsalen, mexiletine, norfloxacin, oral contraceptives, phenylpropanolamine, propafenone, propranolol, terbinafine, thiabendazole, ticlopidine, verapamil …
Source: FDA drug label (Warfarin Sodium), Amneal Pharmaceuticals LLC, effective May 29, 2026 (SPL set 558b7a0d-5490-4c1b-802e-3ab3f1efe760), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Ciprofloxacin | Warfarin | |
|---|---|---|
| Labeled for | Diarrhea, Urinary tract infections, Bacterial infections | Blood clots (DVT and PE), Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.123 per tablet 500 mg tablet | $0.093 per tablet 2 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once