Drug interactions
Dexfenfluramine + Phenylephrine
Severity: Moderate
Dexfenfluramine and Phenylephrine: 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
Dexfenfluramine is a serotonergic anorectic with some sympathomimetic effects. Combined with phenylephrine, blood pressure and heart rate may rise, and the drug is withdrawn in most markets.
What this interaction means in plain words
Dexfenfluramine and Phenylephrine 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 sympathomimetic pressor effects via direct alpha-1 agonism and monoamine release.
What to do
Monitor blood pressure and heart rate if the combination cannot be avoided, and prefer a non-sympathomimetic decongestant.
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
Frequently asked questions
Can I take Dexfenfluramine with Phenylephrine?
MediHelp rates the interaction as moderate. Dexfenfluramine and Phenylephrine 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. Dexfenfluramine is a serotonergic anorectic with some sympathomimetic effects. Combined with phenylephrine, blood pressure and heart rate may rise, and the drug is withdrawn in most markets.
How serious is the interaction between Dexfenfluramine and Phenylephrine?
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 if the combination cannot be avoided, and prefer a non-sympathomimetic decongestant.
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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