Drug interactions
Doxazosin + Phentolamine
Severity: Major
Doxazosin and Phentolamine: 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
Both drugs are alpha-adrenergic antagonists, so combined use can cause marked additive hypotension. Orthostatic hypotension, tachycardia and syncope are possible.
What this interaction means in plain words
Doxazosin and Phentolamine 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.
Doxazosin belongs to Genitourinary; Phentolamine belongs to Cardiovascular.
Why it happens
Additive alpha-adrenergic receptor blockade causing vasodilation.
What to do
Avoid routine concurrent use of two alpha-blockers. If phentolamine is needed, for example in a hypertensive emergency, monitor blood pressure continuously and titrate carefully.
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 Doxazosin
- Alfuzosin + Doxazosin Major
- Amifostine + Doxazosin Major
- Avanafil + Doxazosin Major
- Doxazosin + Dutasteride-tamsulosin Major
- Doxazosin + Prazosin Major
- Doxazosin + Sildenafil Major
Other interactions of Phentolamine
Frequently asked questions
Can I take Doxazosin with Phentolamine?
MediHelp rates the interaction as major. Doxazosin and Phentolamine 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. Both drugs are alpha-adrenergic antagonists, so combined use can cause marked additive hypotension. Orthostatic hypotension, tachycardia and syncope are possible.
How serious is the interaction between Doxazosin and Phentolamine?
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 routine concurrent use of two alpha-blockers. If phentolamine is needed, for example in a hypertensive emergency, monitor blood pressure continuously and titrate carefully.
What other medicines interact with Doxazosin?
MediHelp also lists interactions of Doxazosin with, for example, Alfuzosin, Amifostine, Avanafil. The full list is on the Doxazosin page.
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