Drug interactions
Phenoxybenzamine + Tamsulosin
Severity: Major
Phenoxybenzamine and Tamsulosin: 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 block alpha-adrenergic receptors, so combined use can cause additive vasodilation. This may produce marked orthostatic hypotension, dizziness and syncope.
What this interaction means in plain words
Phenoxybenzamine and Tamsulosin 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 pharmacodynamic alpha-1 adrenergic blockade.
What to do
Avoid combining two alpha-blockers unless specifically intended, for example in pheochromocytoma care. If used together, monitor supine and standing blood pressure and titrate cautiously.
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 Tamsulosin
- Alfuzosin + Tamsulosin Major
- Avanafil + Tamsulosin Major
- Ceritinib + Tamsulosin Major
- Clarithromycin + Tamsulosin Major
- Cobicistat + Tamsulosin Major
- Doxazosin + Tamsulosin Major
Frequently asked questions
Can I take Phenoxybenzamine with Tamsulosin?
MediHelp rates the interaction as major. Phenoxybenzamine and Tamsulosin 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 block alpha-adrenergic receptors, so combined use can cause additive vasodilation. This may produce marked orthostatic hypotension, dizziness and syncope.
How serious is the interaction between Phenoxybenzamine and Tamsulosin?
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 two alpha-blockers unless specifically intended, for example in pheochromocytoma care. If used together, monitor supine and standing blood pressure and titrate cautiously.
What other medicines interact with Tamsulosin?
MediHelp also lists interactions of Tamsulosin with, for example, Alfuzosin, Avanafil, Ceritinib. The full list is on the Tamsulosin page.
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