What the FDA labels say about taking them together
Erlotinib and ketoconazole
Erlotinib's FDA label of June 10, 2024 names ketoconazole in its drug interactions section; the ketoconazole label PlainMeds reads does not name erlotinib. The erlotinib label: “Avoid co-administering erlotinib with strong CYP3A4 inhibitors or a combined CYP3A4 and CYP1A2 inhibitor (e.g., ciprofloxacin).”
Check it at the source: the erlotinib FDA label on DailyMed (effective June 10, 2024, Alembic Pharmaceuticals Limited); the ketoconazole FDA label on DailyMed (effective January 28, 2026, E. Fougera & Co. a division of Fougera Pharmaceuticals, LLC).
What does the erlotinib label say about ketoconazole?
Erlotinib label, drug interactionsAvoid co-administering erlotinib with strong CYP3A4 inhibitors (e.g., boceprevir, clarithromycin, conivaptan, indinavir, itraconazole, ketoconazole, lopinavir/ritonavir, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telithromycin, voriconazole, grapefruit or grapefruit juice) or a combined CYP3A4 and CYP1A2 inhibitor (e.g., ciprofloxacin).
Source: FDA drug label (ERLOTINIB HYDROCHLORIDE), Alembic Pharmaceuticals Limited, effective June 10, 2024 (SPL set ab6f3cb3-34a8-4492-a5d7-fb6b055a2d6b), via openFDA; the full label on DailyMed
What does the ketoconazole label say about erlotinib?
Ketoconazole's label (effective January 28, 2026) does not name erlotinib in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (ketoconazole), E. Fougera & Co. a division of Fougera Pharmaceuticals, LLC, effective January 28, 2026 (SPL set cad7c647-34a9-4e4e-83b3-8d78e58f588f), 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
| Erlotinib | Ketoconazole | |
|---|---|---|
| Labeled for | Lung cancer | Fungal infections |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.249 per gram 2% cream |
| 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