Avanafil and Erythromycin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Erythromycin
Avanafil
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 avanafil exposure and an increased risk of avanafil-related adverse effects
Interaction Deep Dive
Concomitant use of avanafil and erythromycin may result in increased exposure of avanafil that may increase or prolong both the therapeutic and adverse effects. Consider dosage adjustments, and when possible, closely monitor drug concentrations of CYP3A4 substrates in patients concurrently receiving erythromycin234. In a pharmacokinetic study of 15 healthy volunteers, avanafil Cmax and AUC increased 2-fold and 3.6-fold, respectively, when a single 200 mg dose of avanafil was administered on days 1 and 6, and erythromycin 500 mg twice daily was given on days 2 to 6. Results from day 1 were compared with day 6 results. Avanafil doses should not exceed 50 mg once every 24 hours in patients taking erythromycin 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of avanafil
Literature reports
1 report — tap to read
a) In a pharmacokinetic study of 15 healthy volunteers, avanafil Cmax and AUC increased 2-fold and 3.6-fold, respectively, when a single 200 mg dose of avanafil was administered on days 1 and 6, and erythromycin 500 mg twice daily was given on days 2 to 6. Results from day 1 were compared with day 6 results 1.
Common questions
Can I take Avanafil and Erythromycin together?
Increased avanafil exposure and an increased risk of avanafil-related adverse effects Always confirm with your pharmacist or prescriber before making any change.
How serious is the Avanafil and Erythromycin 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Avanafil or Erythromycin 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 (4)
- Product Information: STENDRA(R) oral tablets, avanafil oral tablets. Metuchen Pharmaceuticals LLC (per FDA), Freehold, NJ, 2022. DailyMed
- Product Information: Erythromycin Lactobionate IV injection lyophilized powder for solution, erythromycin lactobionate IV injection lyophilized powder for solution. Nexus Pharmaceuticals (per DailyMed), Lincolnshire, IL, 2024.
- Product Information: Erythromycin oral delayed-release capsules, erythromycin oral delayed-release capsules. Dr. Reddy's Laboratories Inc. (per DailyMed), Princeton, NJ, 2025. DailyMed
- Product Information: ERYTHROMYCIN ETHYLSUCCINATE oral suspension granule, erythromycin ethylsuccinate oral suspension granule. ANI Pharmaceuticals, Inc (per DailyMed), Baudette, MN, 2025. DailyMed
Keep reading about Erythromycin
Keep reading about Avanafil
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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