Esomeprazole and Posaconazole: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Posaconazole
Esomeprazole
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
Reduced posaconazole exposure and reduced efficacy of posaconazole
Interaction Deep Dive
In drug interaction studies, coadministration of posaconazole 400 mg (oral suspension single dose) with esomeprazole 40 mg (every morning for 3 days) resulted in reduced Cmax and AUC of posaconazole by approximately 46% and 32%, respectively12. Hence, avoid concurrent use of NOXAFIL® posaconazole oral suspension with esomeprazole unless the potential benefit outweighs the risk as coadministration may result in reduced exposure to posaconazole, which may reduce the efficacy of posaconazole. If concomitant use is required, monitor the patient closely for breakthrough fungal infections 12.
Why it happens (mechanism)
Reduced bioavailability of posaconazole with increase in gastric pH
Literature reports
2 reports — tap to read
a) Concomitant use of esomeprazole and posaconazole may decrease posaconazole serum concentrations. In a phase 1, randomized, crossover study to evaluate differences in posaconazole absorption with decreased gastric pH, 12 healthy subjects were administered 4 different treatment regimens: (1) a single 400 mg dose of posaconazole while fasting (2) a single 400 mg dose of posaconazole and an acidic carbonated beverage (ginger ale) while fasting, (3) esomeprazole 40 mg daily for 3 days with scheduled meals permitted on days 1 and 2 and on day 3 administration of a single 400 mg dose of posaconazole while fasting, and (4) esomeprazole 40 mg daily for 3 days with scheduled meals permitted on days 1 and 2 and on day 3 administration of a single 400 mg dose of posaconazole with an acidic carbonated beverage while fasting. Compared with results achieved with a single 400 mg dose of posaconazole given alone under fasting conditions, coadministration of esomeprazole elicited reductions in posaconazole mean Cmax and AUC by 46% and 32%, respectively. Administration of posaconazole, an acidic carbonated beverage and esomeprazole together, elicited reductions in the mean posaconazole Cmax and AUC by 33% and 21%, respectively 3.
b) In drug interaction studies, coadministration of posaconazole 400 mg (oral suspension single dose) with esomeprazole 40 mg (every morning for 3 days) resulted in reduced Cmax and AUC of posaconazole by approximately 46% and 32%, respectively 12.
Common questions
Can I take Esomeprazole and Posaconazole together?
Reduced posaconazole exposure and reduced efficacy of posaconazole Always confirm with your pharmacist or prescriber before making any change.
How serious is the Esomeprazole and Posaconazole interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Esomeprazole or Posaconazole 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: NOXAFIL® PowderMix delayed-release oral suspension, posaconazole delayed-release oral suspension. Merck Sharp & Dohme LLC (per FDA), Rahway, NJ, 2026. DailyMed
- Product Information: NOXAFIL® intravenous injection, oral delayed-release tablets, oral suspension, posaconazole intravenous injection, oral delayed-release tablets, oral suspension. Merck Sharp & Dohme LLC (per FDA), Rahway, NJ, 2026. DailyMed
- Krishna G, Moton A, Ma L, et al: The pharmacokinetics and absorption of posaconazole oral suspension under various gastric conditions in healthy volunteers. Antimicrob Agents Chemother 2009; 53(3):958-966. PubMed
Keep reading about Posaconazole
Keep reading about Esomeprazole
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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