Drug interactions
Phenylephrine po + Promethazine
Severity: Minor
Phenylephrine po and Promethazine: minor 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
Oral phenylephrine is a decongestant with alpha-agonist activity, while promethazine is sedating and has alpha-blocking properties. Effects on sedation and blood pressure may partially oppose each other, and both can affect heart rhythm in vulnerable patients.
What this interaction means in plain words
Phenylephrine po and Promethazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Pharmacodynamic opposition at adrenergic receptors and CNS; no well-defined mechanism for clinically significant harm.
What to do
Monitor blood pressure and heart rate in patients with cardiovascular disease. No routine dose adjustment is needed for most patients.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Phenylephrine po with Promethazine?
MediHelp rates the interaction as minor. Phenylephrine po and Promethazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Oral phenylephrine is a decongestant with alpha-agonist activity, while promethazine is sedating and has alpha-blocking properties. Effects on sedation and blood pressure may partially oppose each other, and both can affect heart rhythm in vulnerable patients.
How serious is the interaction between Phenylephrine po and Promethazine?
MediHelp rates it minor, 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 in patients with cardiovascular disease. No routine dose adjustment is needed for most patients.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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