Drug interactions
Phentolamine + Prazosin
Severity: Moderate
Phentolamine and Prazosin: moderate 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 blockers, and combining them gives additive vasodilation. This can cause significant hypotension, dizziness and syncope.
What this interaction means in plain words
Phentolamine and Prazosin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Phentolamine belongs to Cardiovascular; Prazosin belongs to Genitourinary.
Why it happens
Additive alpha-1 adrenergic receptor blockade.
What to do
Monitor blood pressure and orthostatic symptoms, and reduce the dose of one agent if hypotension occurs. Avoid duplicate alpha-blockade unless clearly intended.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Phentolamine
Other interactions of Prazosin
- Alfuzosin + Prazosin Major
- Amifostine + Prazosin Major
- Avanafil + Prazosin Major
- Doxazosin + Prazosin Major
- Dutasteride-tamsulosin + Prazosin Major
- Phenoxybenzamine + Prazosin Major
Frequently asked questions
Can I take Phentolamine with Prazosin?
MediHelp rates the interaction as moderate. Phentolamine and Prazosin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Both drugs are alpha-adrenergic blockers, and combining them gives additive vasodilation. This can cause significant hypotension, dizziness and syncope.
How serious is the interaction between Phentolamine and Prazosin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure and orthostatic symptoms, and reduce the dose of one agent if hypotension occurs. Avoid duplicate alpha-blockade unless clearly intended.
What other medicines interact with Phentolamine?
MediHelp also lists interactions of Phentolamine with, for example, Alfuzosin, Avanafil, Doxazosin. The full list is on the Phentolamine page.
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