Lansoprazole and Fluconazole: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fluconazole
Lansoprazole
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 CYP2C19 substrate exposure and an increased risk of CYP2C19 substrate-related adverse events
Interaction Deep Dive
Use caution when coadministering fluconazole (a CYP2C19 inhibitor) and a CYP2C19 substrate due to the risk of increased exposure of the CYP2C19 substrate. Fluconazole-mediated enzyme inhibition may persist for 4 to 5 days after discontinuation. If concomitant use is required, carefully monitor the patient1.
Why it happens (mechanism)
Inhibition of CYP2C19-mediated substrate metabolism by fluconazole
Common questions
Can I take Lansoprazole and Fluconazole together?
Increased CYP2C19 substrate exposure and an increased risk of CYP2C19 substrate-related adverse events Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lansoprazole and Fluconazole 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Lansoprazole or Fluconazole 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 (1)
- Product Information: DIFLUCAN(R) oral tablets, suspension, fluconazole oral tablets, suspension. Roerig (per FDA), New York, NY, 2024. DailyMed
Keep reading about Fluconazole
Keep reading about Lansoprazole
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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