What the FDA labels say about taking them together
Ascorbic acid and warfarin
Ascorbic acid's FDA label of May 29, 2026 names warfarin in its drug interactions section; the warfarin label PlainMeds reads does not name ascorbic acid. The ascorbic acid label: “… excretion and plasma concentrations of other drugs sensitive to urine pH. Warfarin: Continue standard monitoring See 17 for PATIENT COUNSELING INFORMATION Antibiotics: Ascorbic acid may decrease the activities of …”
Check it at the source: the ascorbic acid FDA label on DailyMed (effective May 29, 2026, McGuff Pharmaceuticals, Inc.); the warfarin FDA label on DailyMed (effective May 29, 2026, Amneal Pharmaceuticals LLC).
What does the ascorbic acid label say about warfarin?
Ascorbic acid label, drug interactionsBleomycin is inactivated in vitro by ascorbic acid (7.1). Amphetamine and Other Drugs Affected by Urine Acidification: Ascorbic acid may cause acidification of the urine and result in decreased amphetamine serum levels affect excretion and plasma concentrations of other drugs sensitive to urine pH (7.2). Warfarin: Continue standard monitoring (7.3) See 17 for PATIENT COUNSELING INFORMATION Antibiotics: Ascorbic acid may decrease the activities of erythromycin, kanamycin, streptomycin, doxycycline, and lincomycin.
Source: FDA drug label (Ascor), McGuff Pharmaceuticals, Inc., effective May 29, 2026 (SPL set 388aad52-fc01-4784-9791-1dbc80c69306), via openFDA; the full label on DailyMed
What does the warfarin label say about ascorbic acid?
Warfarin's label (effective May 29, 2026) does not name ascorbic acid 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
| Ascorbic acid | Warfarin | |
|---|---|---|
| Labeled for | n/a | 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