Drug interactions
Avanafil + Phenytoin
Severity: Moderate
Avanafil and Phenytoin: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Phenytoin induces CYP3A4 and can reduce avanafil concentrations, possibly leading to loss of efficacy for erectile dysfunction.
What this interaction means in plain words
Avanafil and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Avanafil belongs to Genitourinary; Phenytoin belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 increases avanafil metabolism.
What to do
Monitor erectile response and consider an alternative therapy if avanafil becomes ineffective.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Avanafil and Phenytoin, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Avanafil
- Amyl nitrite + Avanafil Contraindicated
- Atazanavir + Avanafil Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Avanafil + Conivaptan Contraindicated
- Avanafil + Darunavir Contraindicated
- Avanafil + Fosamprenavir Contraindicated
Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Avanafil with Phenytoin?
MediHelp rates the interaction as moderate. Avanafil and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phenytoin induces CYP3A4 and can reduce avanafil concentrations, possibly leading to loss of efficacy for erectile dysfunction.
How serious is the interaction between Avanafil and Phenytoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor erectile response and consider an alternative therapy if avanafil becomes ineffective.
What other medicines interact with Avanafil?
MediHelp also lists interactions of Avanafil with, for example, Amyl nitrite, Atazanavir, Clarithromycin. The full list is on the Avanafil page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
