Drug interactions
Phentolamine + Tadalafil
Severity: Major
Phentolamine and Tadalafil: major 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
Phentolamine is an alpha blocker that causes vasodilation, and tadalafil adds to this effect. The combination may cause marked hypotension, dizziness or syncope.
What this interaction means in plain words
Phentolamine 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.
Phentolamine belongs to Cardiovascular; Tadalafil belongs to Genitourinary.
Why it happens
Additive vasodilation from PDE5 inhibition and alpha-adrenergic blockade.
What to do
Avoid combining unless benefits clearly outweigh risk. If used, give the lowest tadalafil dose with blood pressure monitoring, and avoid within a few hours of parenteral phentolamine.
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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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 Phentolamine
Frequently asked questions
Can I take Phentolamine with Tadalafil?
MediHelp rates the interaction as major. Phentolamine 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. Phentolamine is an alpha blocker that causes vasodilation, and tadalafil adds to this effect. The combination may cause marked hypotension, dizziness or syncope.
How serious is the interaction between Phentolamine 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: Avoid combining unless benefits clearly outweigh risk. If used, give the lowest tadalafil dose with blood pressure monitoring, and avoid within a few hours of parenteral phentolamine.
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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