What the FDA labels say about taking them together
Ivacaftor and ketoconazole
Ivacaftor's FDA label of March 23, 2026 names ketoconazole in its drug interactions section; the ketoconazole label PlainMeds reads does not name ivacaftor. The ivacaftor label: “… months and older when co-administered with strong CYP3A inhibitors (e.g., ketoconazole) or moderate CYP3A inhibitors (e.g., fluconazole).”
Check it at the source: the ivacaftor FDA label on DailyMed (effective March 23, 2026, Vertex Pharmaceuticals Incorporated); the ketoconazole FDA label on DailyMed (effective January 28, 2026, E. Fougera & Co. a division of Fougera Pharmaceuticals, LLC).
What does the ivacaftor label say about ketoconazole?
Ivacaftor label, drug interactionsDRUG INTERACTIONS Potential for other drugs to affect ivacaftor CYP3A inhibitors: Reduce KALYDECO dosage in patients aged 6 months and older when co-administered with strong CYP3A inhibitors (e.g., ketoconazole) or moderate CYP3A inhibitors (e.g., fluconazole).
Source: FDA drug label (Kalydeco), Vertex Pharmaceuticals Incorporated, effective March 23, 2026 (SPL set 0ab0c9f8-3eee-4e0f-9f3f-c1e16aaffe25), via openFDA; the full label on DailyMed
What does the ketoconazole label say about ivacaftor?
Ketoconazole's label (effective January 28, 2026) does not name ivacaftor 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
| Ivacaftor | Ketoconazole | |
|---|---|---|
| Labeled for | n/a | 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