What the FDA labels say about taking them together
Siltuximab and warfarin
Siltuximab's FDA label of August 27, 2024 names warfarin in its drug interactions section; the warfarin label PlainMeds reads does not name siltuximab. The siltuximab label: “… narrow therapeutic index, perform therapeutic monitoring of effect (e.g., warfarin) or drug concentration as needed and adjust dose.”
Check it at the source: the siltuximab FDA label on DailyMed (effective August 27, 2024); the warfarin FDA label on DailyMed (effective May 29, 2026, Amneal Pharmaceuticals LLC).
What does the siltuximab label say about warfarin?
Siltuximab label, drug interactionsUpon initiation or discontinuation of SYLVANT, in patients being treated with CYP450 substrates with a narrow therapeutic index, perform therapeutic monitoring of effect (e.g., warfarin) or drug concentration (e.g., cyclosporine or theophylline) as needed and adjust dose.
Source: FDA drug label (Sylvant), Recordati Rare Diseases, Inc., effective August 27, 2024 (SPL set 8d663642-f52e-49c0-a023-2da083fdfc0b), via openFDA; the full label on DailyMed
What does the warfarin label say about siltuximab?
Warfarin's label (effective May 29, 2026) does not name siltuximab 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
| Siltuximab | 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