Tezacaftor and Ketoconazole Topical: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ketoconazole Topical
Tezacaftor
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased tezacaftor exposure and an increased risk of tezacaftor-related adverse reactions
Interaction Deep Dive
Concomitant use of tezacaftor-containing products and a strong CYP3A inhibitor may increase tezacaftor exposure. Reduce the tezacaftor dosage with concomitant use. For 6 to less than 12 years old, patients weighing less than 40 kg adjust the dose to two tablets of vanzacaftor 4 mg/tezacaftor 20 mg/deutivacaftor 50 mg once a week and for patients greater than or equal to 40 kg adjust the dose to one tablet of vanzacaftor 10 mg/tezacaftor 50 mg/deutivacaftor 125 mg once a week. For 12 years and older patients adjust the dose to one tablet of vanzacaftor 10 mg/tezacaftor 50 mg/deutivacaftor 125 mg once a week1. For tezacaftor/ivacaftor, give tezacaftor 100 mg/ivacaftor 150 mg orally in the morning on day 1 and day 4 (do not give evening doses of ivacaftor and do not give any doses on day 2 or 3), then continue administering this dose twice weekly (every 3 to 4 days) 2. For elexacaftor/tezacaftor/ivacaftor, give 2 tablets (elexacaftor 100 mg/tezacaftor 50 mg/ivacaftor 75 mg per tablet) orally in the morning on day 1 and day 4 (do not give evening doses of ivacaftor and do not give any doses on day 2 or 3), then continue administering this dose twice weekly (every 3 to 4 days) during concomitant use with the strong CYP3A inhibitor 3.
Why it happens (mechanism)
Inhibition of CYP3A-mediated metabolism of tezacaftor
Literature reports
3 reports — tap to read
a) Coadministration of tezacaftor 25 mg and ivacaftor 50 mg orally once daily with strong CYP3A inhibitor itraconazole 200 mg orally twice daily on day 1, followed by 200 mg once daily increased tezacaftor AUC by 4.02-fold and Cmax by 2.83-fold, and increased ivacaftor AUC by 15.6-fold and Cmax by 8.6-fold 231.
b) Coadministration of a single dose of elexacaftor 20 mg and tezacaftor 50 mg with the strong CYP3A inhibitor itraconazole 200 mg daily increased elexacaftor AUC by 2.83-fold and Cmax by 1.05-fold, and tezacaftor AUC by 4.51-fold and Cmax by 1.48-fold 3.
c) Coadministration of a single dose of elexacaftor 20 mg, tezacaftor 50 mg and deutivacaftor 50 mg with the strong CYP3A inhibitor itraconazole 200 mg daily increased deutivacaftor AUC by 11.1-fold and Cmax by 1.96-fold, and tezacaftor AUC by 4.51-fold and Cmax by 1.48-fold 1.
Common questions
Can I take Tezacaftor and Ketoconazole Topical together?
Increased tezacaftor exposure and an increased risk of tezacaftor-related adverse reactions Always confirm with your pharmacist or prescriber before making any change.
How serious is the Tezacaftor and Ketoconazole Topical interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Tezacaftor or Ketoconazole Topical need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (3)
- Product Information: ALYFTREK(R) oral tablets, vanzacaftor, tezacaftor, and deutivacaftor oral tablets. Vertex Pharmaceuticals Incorporated (per FDA), Boston, MA, 2024. DailyMed
- Product Information: SYMDEKO(TM) oral tablets, tezacaftor ivacaftor oral tablets and ivacaftor oral tablets. Vertex Pharmaceuticals Incorporated (per manufacturer), Boston, MA, 2019. DailyMed
- Product Information: TRIKAFTA(R) oral tablets oral granules, elexacaftor, tezacaftor, ivacaftor oral tablets oral granules; ivacaftor oral tablets oral granules. Vertex Pharmaceuticals Incorporated (per FDA), Boston, MA, 2024. DailyMed
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