Drug interactions
Labetalol + Phenoxybenzamine
Severity: Moderate
Labetalol 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
Both drugs block alpha-adrenergic receptors, and phenoxybenzamine does so irreversibly, so the combination can produce marked hypotension and orthostatic symptoms. In pheochromocytoma, beta blockade given without adequate alpha blockade can be hazardous, although here alpha blockade is present.
What this interaction means in plain words
Labetalol 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 alpha-adrenergic blockade, with added beta blockade from labetalol, lowering vascular tone and blood pressure.
What to do
Monitor blood pressure and heart rate closely, including standing values, and introduce labetalol at a low dose. Adjust either drug if hypotension or marked bradycardia 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?
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Other interactions of Labetalol
- Amifostine + Labetalol Major
- Amiodarone + Labetalol Major
- Atenolol-chlorthalidone + Labetalol Major
- Atenolol + Labetalol Major
- Betaxolol + Labetalol Major
- Bisoprolol + Labetalol Major
Frequently asked questions
Can I take Labetalol with Phenoxybenzamine?
MediHelp rates the interaction as moderate. Labetalol 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. Both drugs block alpha-adrenergic receptors, and phenoxybenzamine does so irreversibly, so the combination can produce marked hypotension and orthostatic symptoms. In pheochromocytoma, beta blockade given without adequate alpha blockade can be hazardous, although here alpha blockade is present.
How serious is the interaction between Labetalol 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: Monitor blood pressure and heart rate closely, including standing values, and introduce labetalol at a low dose. Adjust either drug if hypotension or marked bradycardia occurs.
What other medicines interact with Labetalol?
MediHelp also lists interactions of Labetalol with, for example, Amifostine, Amiodarone, Atenolol-chlorthalidone. The full list is on the Labetalol page.
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