Drug interactions
Phenylephrine po + Pseudoephedrine
Severity: Moderate
Phenylephrine po and Pseudoephedrine: 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 are oral decongestants with sympathomimetic activity, so using them together offers no extra benefit and can raise blood pressure and heart rate. This often happens inadvertently with multiple combination cold products.
What this interaction means in plain words
Phenylephrine po and Pseudoephedrine 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
Duplicate adrenergic stimulation: pseudoephedrine acts indirectly while phenylephrine is a direct alpha-1 agonist.
What to do
Avoid combining two decongestants and check ingredients of OTC products. Monitor blood pressure if both have been taken.
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 Pseudoephedrine
- Isocarboxazid + Pseudoephedrine Contraindicated
- Phenelzine + Pseudoephedrine Contraindicated
- Pseudoephedrine + Rasagiline Contraindicated
- Pseudoephedrine + Selegiline Contraindicated
- Pseudoephedrine + Selegiline transdermal Contraindicated
- Pseudoephedrine + Tranylcypromine Contraindicated
Frequently asked questions
Can I take Phenylephrine po with Pseudoephedrine?
MediHelp rates the interaction as moderate. Phenylephrine po and Pseudoephedrine 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 are oral decongestants with sympathomimetic activity, so using them together offers no extra benefit and can raise blood pressure and heart rate. This often happens inadvertently with multiple combination cold products.
How serious is the interaction between Phenylephrine po and Pseudoephedrine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining two decongestants and check ingredients of OTC products. Monitor blood pressure if both have been taken.
What other medicines interact with Pseudoephedrine?
MediHelp also lists interactions of Pseudoephedrine with, for example, Isocarboxazid, Phenelzine, Rasagiline. The full list is on the Pseudoephedrine page.
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