Drug interactions
Phenytoin + Vardenafil
Severity: Moderate
Phenytoin and Vardenafil: 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 is a potent inducer of CYP3A4 and can substantially lower vardenafil exposure, so the drug may become ineffective.
What this interaction means in plain words
Phenytoin and Vardenafil 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 belongs to Central Nervous System; Vardenafil belongs to Genitourinary.
Why it happens
Induction of CYP3A4 increases the metabolic clearance of vardenafil.
What to do
Monitor erectile response and consider an alternative therapy if vardenafil fails at the maximum labeled dose.
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?
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Other interactions of Vardenafil
- Amyl nitrite + Vardenafil Contraindicated
- Glyceryl trinitrate pr + Vardenafil Contraindicated
- Isosorbide dinitrate + Vardenafil Contraindicated
- Isosorbide mononitrate + Vardenafil Contraindicated
- Nicorandil + Vardenafil Contraindicated
- Nitroglycerin po + Vardenafil 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 Phenytoin with Vardenafil?
MediHelp rates the interaction as moderate. Phenytoin and Vardenafil 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 is a potent inducer of CYP3A4 and can substantially lower vardenafil exposure, so the drug may become ineffective.
How serious is the interaction between Phenytoin and Vardenafil?
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 vardenafil fails at the maximum labeled dose.
What other medicines interact with Vardenafil?
MediHelp also lists interactions of Vardenafil with, for example, Amyl nitrite, Glyceryl trinitrate pr, Isosorbide dinitrate. The full list is on the Vardenafil page.
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