Drug interactions
Phenoxybenzamine + Prazosin
Severity: Major
Phenoxybenzamine and Prazosin: 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 agents block alpha-adrenergic receptors, and phenoxybenzamine does so irreversibly. Combined use can cause profound hypotension, orthostatic symptoms and reflex tachycardia, with little added benefit.
What this interaction means in plain words
Phenoxybenzamine and Prazosin 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.
Why it happens
Additive alpha-adrenergic receptor blockade producing vasodilation.
What to do
Avoid routine combination. If used, for example in pheochromocytoma, give under specialist supervision with close monitoring of supine and standing blood pressure.
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 Prazosin
- Alfuzosin + Prazosin Major
- Amifostine + Prazosin Major
- Avanafil + Prazosin Major
- Doxazosin + Prazosin Major
- Dutasteride-tamsulosin + Prazosin Major
- Prazosin + Sildenafil Major
Frequently asked questions
Can I take Phenoxybenzamine with Prazosin?
MediHelp rates the interaction as major. Phenoxybenzamine and Prazosin 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 agents block alpha-adrenergic receptors, and phenoxybenzamine does so irreversibly. Combined use can cause profound hypotension, orthostatic symptoms and reflex tachycardia, with little added benefit.
How serious is the interaction between Phenoxybenzamine and Prazosin?
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 combination. If used, for example in pheochromocytoma, give under specialist supervision with close monitoring of supine and standing blood pressure.
What other medicines interact with Prazosin?
MediHelp also lists interactions of Prazosin with, for example, Alfuzosin, Amifostine, Avanafil. The full list is on the Prazosin page.
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