What the FDA labels say about taking them together
Gefitinib and ketoconazole
Gefitinib's FDA label of February 28, 2023 names ketoconazole in its drug interactions section; the ketoconazole label PlainMeds reads does not name gefitinib. The gefitinib label: “CYP3A4 Inhibitor Drugs that are strong inhibitors of CYP3A4 decrease gefitinib metabolism and increase gefitinib plasma concentrations.”
Check it at the source: the gefitinib FDA label on DailyMed (effective February 28, 2023, AstraZeneca Pharmaceuticals LP); the ketoconazole FDA label on DailyMed (effective January 28, 2026, E. Fougera & Co. a division of Fougera Pharmaceuticals, LLC).
What does the gefitinib label say about ketoconazole?
Gefitinib label, drug interactionsCYP3A4 Inhibitor Drugs that are strong inhibitors of CYP3A4 (e.g., ketoconazole and itraconazole) decrease gefitinib metabolism and increase gefitinib plasma concentrations.
Source: FDA drug label (IRESSA), AstraZeneca Pharmaceuticals LP, effective February 28, 2023 (SPL set 827d60e8-7e07-41b7-c28b-49ef1c4a5a41), via openFDA; the full label on DailyMed
What does the ketoconazole label say about gefitinib?
Ketoconazole's label (effective January 28, 2026) does not name gefitinib 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
| Gefitinib | 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