Drug interactions
Phenylephrine + Prazosin
Severity: Moderate
Phenylephrine 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
Prazosin blocks alpha-1 receptors and can blunt the pressor response to phenylephrine. This may reduce the effectiveness of phenylephrine used for hypotension or decongestion.
What this interaction means in plain words
Phenylephrine 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.
Phenylephrine belongs to Respiratory; Prazosin belongs to Genitourinary.
Why it happens
Pharmacodynamic antagonism at alpha-1 adrenergic receptors.
What to do
Monitor blood pressure and titrate phenylephrine to response. Avoid oral phenylephrine decongestants where blood pressure control is a concern.
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 Phenylephrine
- Isocarboxazid + Phenylephrine Contraindicated
- Phenelzine + Phenylephrine Contraindicated
- Phenylephrine + Tranylcypromine Contraindicated
- Bromocriptine + Phenylephrine Major
- Cocaine + Phenylephrine Major
- Dihydroergotamine intranasal + Phenylephrine Major
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 Phenylephrine with Prazosin?
MediHelp rates the interaction as moderate. Phenylephrine 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. Prazosin blocks alpha-1 receptors and can blunt the pressor response to phenylephrine. This may reduce the effectiveness of phenylephrine used for hypotension or decongestion.
How serious is the interaction between Phenylephrine 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 titrate phenylephrine to response. Avoid oral phenylephrine decongestants where blood pressure control is a concern.
What other medicines interact with Phenylephrine?
MediHelp also lists interactions of Phenylephrine with, for example, Isocarboxazid, Phenelzine, Tranylcypromine. The full list is on the Phenylephrine page.
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