What the FDA labels say about taking them together
Rifaximin and warfarin
Rifaximin's FDA label of June 25, 2025 names warfarin in its drug interactions section; the warfarin label PlainMeds reads does not name rifaximin. The rifaximin label: “DRUG INTERACTIONS Warfarin: Monitor INR and prothrombin time; dose adjustment of warfarin may be needed to maintain target INR range.”
Check it at the source: the rifaximin FDA label on DailyMed (effective June 25, 2025, Salix Pharmaceuticals, Inc.); the warfarin FDA label on DailyMed (effective May 29, 2026, Amneal Pharmaceuticals LLC).
What does the rifaximin label say about warfarin?
Rifaximin label, drug interactionsDRUG INTERACTIONS Warfarin: Monitor INR and prothrombin time; dose adjustment of warfarin may be needed to maintain target INR range.
Source: FDA drug label (XIFAXAN), Salix Pharmaceuticals, Inc., effective June 25, 2025 (SPL set c5e8e2fd-7087-4b78-9181-cc259c0be2f1), via openFDA; the full label on DailyMed
What does the warfarin label say about rifaximin?
Warfarin's label (effective May 29, 2026) does not name rifaximin in these sections. A label lists what its studies and reports found; it is not a complete list.
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
| Rifaximin | Warfarin | |
|---|---|---|
| Labeled for | Diarrhea, Irritable bowel syndrome | Blood clots (DVT and PE), Atrial fibrillation |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $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