Drug interactions
Atazanavir + Tadalafil
Severity: Major
Atazanavir and Tadalafil: major interaction.
Last updated Sources: US FDA label
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
Atazanavir inhibits CYP3A4 and substantially increases tadalafil exposure. This raises the risk of hypotension, visual disturbance, priapism and syncope.
What this interaction means in plain words
Atazanavir and Tadalafil can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Atazanavir belongs to Anti Virals; Tadalafil belongs to Genitourinary.
Why it happens
Inhibition of CYP3A4-mediated tadalafil metabolism by atazanavir.
What to do
For PAH, stop tadalafil at least 24 hours before starting the protease inhibitor and restart after about a week at 20 mg daily, titrating as tolerated. For ED, use a reduced dose with a long interval between doses.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Tadalafil
- Amyl nitrite + Tadalafil Contraindicated
- Isosorbide dinitrate + Tadalafil Contraindicated
- Isosorbide mononitrate + Tadalafil Contraindicated
- Nitroglycerin po + Tadalafil Contraindicated
- Nitroglycerin rectal + Tadalafil Contraindicated
- Nitroglycerin sublingual + Tadalafil Contraindicated
Other interactions of Atazanavir
- Alfuzosin + Atazanavir Contraindicated
- Atazanavir + Avanafil Contraindicated
- Atazanavir + Dronedarone Contraindicated
- Atazanavir + Eletriptan Contraindicated
- Atazanavir + Eplerenone Contraindicated
- Atazanavir + Ergotamine Contraindicated
Frequently asked questions
Can I take Atazanavir with Tadalafil?
MediHelp rates the interaction as major. Atazanavir and Tadalafil can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Atazanavir inhibits CYP3A4 and substantially increases tadalafil exposure. This raises the risk of hypotension, visual disturbance, priapism and syncope.
How serious is the interaction between Atazanavir and Tadalafil?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: For PAH, stop tadalafil at least 24 hours before starting the protease inhibitor and restart after about a week at 20 mg daily, titrating as tolerated. For ED, use a reduced dose with a long interval between doses.
What other medicines interact with Tadalafil?
MediHelp also lists interactions of Tadalafil with, for example, Amyl nitrite, Isosorbide dinitrate, Isosorbide mononitrate. The full list is on the Tadalafil page.
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