Drug interactions
Nelfinavir + Sildenafil
Severity: Contraindicated
Nelfinavir and Sildenafil: contraindicated 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
Nelfinavir inhibits CYP3A4 and can increase sildenafil levels significantly. Excess exposure raises the risk of hypotension, syncope, visual changes and priapism.
What this interaction means in plain words
Nelfinavir and Sildenafil are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Nelfinavir belongs to Anti Virals; Sildenafil belongs to Genitourinary.
Why it happens
Nelfinavir inhibits CYP3A4-mediated metabolism of sildenafil.
What to do
Avoid for pulmonary arterial hypertension. If used for erectile dysfunction, start at 25 mg with no more than one dose per 48 hours and monitor blood pressure.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Sildenafil
- Amyl nitrite + Sildenafil Contraindicated
- Atazanavir + Sildenafil Contraindicated
- Cobicistat + Sildenafil Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Sildenafil Contraindicated
- Glyceryl trinitrate pr + Sildenafil Contraindicated
- Isosorbide dinitrate + Sildenafil Contraindicated
Other interactions of Nelfinavir
- Alfuzosin + Nelfinavir Contraindicated
- Avanafil + Nelfinavir Contraindicated
- Dronedarone + Nelfinavir Contraindicated
- Eletriptan + Nelfinavir Contraindicated
- Ergotamine + Nelfinavir Contraindicated
- Flibanserin + Nelfinavir Contraindicated
Frequently asked questions
Can I take Nelfinavir with Sildenafil?
MediHelp rates the interaction as contraindicated. Nelfinavir and Sildenafil are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Nelfinavir inhibits CYP3A4 and can increase sildenafil levels significantly. Excess exposure raises the risk of hypotension, syncope, visual changes and priapism.
How serious is the interaction between Nelfinavir and Sildenafil?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid for pulmonary arterial hypertension. If used for erectile dysfunction, start at 25 mg with no more than one dose per 48 hours and monitor blood pressure.
What other medicines interact with Sildenafil?
MediHelp also lists interactions of Sildenafil with, for example, Amyl nitrite, Atazanavir, Cobicistat. The full list is on the Sildenafil page.
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