Drug interactions
Phentolamine + Propranolol
Severity: Moderate
Phentolamine and Propranolol: 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
Phentolamine is an alpha-blocking vasodilator and propranolol blocks beta receptors, so together they lower blood pressure more than either alone. Phentolamine also causes reflex tachycardia that propranolol may blunt. Excessive hypotension can occur, particularly with parenteral phentolamine.
What this interaction means in plain words
Phentolamine and Propranolol 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; Propranolol belongs to Cardiovascular.
Why it happens
Additive pharmacodynamic hypotensive effects from alpha-adrenergic blockade combined with beta-adrenergic blockade.
What to do
Monitor blood pressure and heart rate when combining them, and titrate doses gradually. Have supine positioning and fluids available when phentolamine is given parenterally.
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 Propranolol
- Propranolol + Thioridazine Contraindicated
- Acebutolol + Propranolol Major
- Adrenaline-articaine + Propranolol Major
- Albuterol + Propranolol Major
- Amifostine + Propranolol Major
- Amiodarone + Propranolol Major
Other interactions of Phentolamine
Frequently asked questions
Can I take Phentolamine with Propranolol?
MediHelp rates the interaction as moderate. Phentolamine and Propranolol 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 is an alpha-blocking vasodilator and propranolol blocks beta receptors, so together they lower blood pressure more than either alone. Phentolamine also causes reflex tachycardia that propranolol may blunt. Excessive hypotension can occur, particularly with parenteral phentolamine.
How serious is the interaction between Phentolamine and Propranolol?
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 heart rate when combining them, and titrate doses gradually. Have supine positioning and fluids available when phentolamine is given parenterally.
What other medicines interact with Propranolol?
MediHelp also lists interactions of Propranolol with, for example, Thioridazine, Acebutolol, Adrenaline-articaine. The full list is on the Propranolol page.
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