What the FDA labels say about taking them together
Propylthiouracil and warfarin
Propylthiouracil's FDA label of August 27, 2026 names warfarin in its drug interactions section; the warfarin label PlainMeds reads does not name propylthiouracil. The propylthiouracil label: “Drug Interactions Anticoagulants (oral): Due to the potential inhibition of vitamin K activity by propylthiouracil, the activity of oral anticoagulants (e.g., warfarin) may be increased; …”
Check it at the source: the propylthiouracil FDA label on DailyMed (effective August 27, 2026, American Health Packaging); the warfarin FDA label on DailyMed (effective May 29, 2026, Amneal Pharmaceuticals LLC).
What does the propylthiouracil label say about warfarin?
Propylthiouracil label, drug interactionsDrug Interactions Anticoagulants (oral): Due to the potential inhibition of vitamin K activity by propylthiouracil, the activity of oral anticoagulants (e.g., warfarin) may be increased; additional monitoring of PT/INR should be considered, especially before surgical procedures.
Source: FDA drug label (Propylthiouracil), American Health Packaging, effective August 27, 2026 (SPL set d819e532-09ac-434a-84a6-636c4204c7aa), via openFDA; the full label on DailyMed
What does the warfarin label say about propylthiouracil?
Warfarin's label (effective May 29, 2026) does not name propylthiouracil 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
| Propylthiouracil | Warfarin | |
|---|---|---|
| Labeled for | n/a | Blood clots (DVT and PE), Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.269 per tablet 50 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