Drug interactions
Metoprolol + Phenoxybenzamine
Severity: Moderate
Metoprolol and Phenoxybenzamine: 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
Phenoxybenzamine causes irreversible alpha-blockade and marked vasodilation, and metoprolol adds to the blood pressure lowering. In pheochromocytoma, a beta-blocker is given only after alpha-blockade is established to avoid hypertensive crisis from unopposed alpha stimulation.
What this interaction means in plain words
Metoprolol and Phenoxybenzamine 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.
Why it happens
Additive hypotension from alpha-adrenergic and beta-adrenergic blockade.
What to do
Start the beta-blocker only after adequate alpha-blockade, and monitor blood pressure including standing readings. Reduce doses if orthostatic hypotension occurs.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Metoprolol and Phenoxybenzamine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Metoprolol
- Metoprolol + Thioridazine Contraindicated
- Amifostine + Metoprolol Major
- Amiodarone + Metoprolol Major
- Atenolol-chlorthalidone + Metoprolol Major
- Atenolol + Metoprolol Major
- Betaxolol + Metoprolol Major
Frequently asked questions
Can I take Metoprolol with Phenoxybenzamine?
MediHelp rates the interaction as moderate. Metoprolol and Phenoxybenzamine 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. Phenoxybenzamine causes irreversible alpha-blockade and marked vasodilation, and metoprolol adds to the blood pressure lowering. In pheochromocytoma, a beta-blocker is given only after alpha-blockade is established to avoid hypertensive crisis from unopposed alpha stimulation.
How serious is the interaction between Metoprolol and Phenoxybenzamine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Start the beta-blocker only after adequate alpha-blockade, and monitor blood pressure including standing readings. Reduce doses if orthostatic hypotension occurs.
What other medicines interact with Metoprolol?
MediHelp also lists interactions of Metoprolol with, for example, Thioridazine, Amifostine, Amiodarone. The full list is on the Metoprolol page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
