Drug interactions
Ephedrine + Phentolamine
Severity: Moderate
Ephedrine and Phentolamine: 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 blocks alpha-adrenergic receptors and can reduce the pressor effect of ephedrine, leaving beta-mediated vasodilation and tachycardia unopposed. This may cause hypotension and rapid heart rate and reduce the effectiveness of ephedrine for hypotension.
What this interaction means in plain words
Ephedrine and Phentolamine 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.
Ephedrine belongs to Cardiovascular; Phentolamine belongs to Cardiovascular.
Why it happens
Alpha-adrenergic blockade by phentolamine antagonizes the vasoconstrictor effect of ephedrine.
What to do
Monitor blood pressure and heart rate closely. Use a non-adrenergic or direct vasopressor and avoid relying on ephedrine to correct phentolamine-induced hypotension.
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 Ephedrine
- Ephedrine + Isocarboxazid Contraindicated
- Ephedrine + Phenelzine Contraindicated
- Ephedrine + Procarbazine Contraindicated
- Ephedrine + Rasagiline Contraindicated
- Ephedrine + Selegiline Contraindicated
- Ephedrine + Tranylcypromine Contraindicated
Frequently asked questions
Can I take Ephedrine with Phentolamine?
MediHelp rates the interaction as moderate. Ephedrine and Phentolamine 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 blocks alpha-adrenergic receptors and can reduce the pressor effect of ephedrine, leaving beta-mediated vasodilation and tachycardia unopposed. This may cause hypotension and rapid heart rate and reduce the effectiveness of ephedrine for hypotension.
How serious is the interaction between Ephedrine and Phentolamine?
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 closely. Use a non-adrenergic or direct vasopressor and avoid relying on ephedrine to correct phentolamine-induced hypotension.
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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