Drug interactions
Phendimetrazine + Phenylephrine
Severity: Moderate
Phendimetrazine 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
Phendimetrazine is a sympathomimetic anorectic and phenylephrine is a vasopressor and decongestant. Combined use can add to increases in blood pressure and heart rate and may provoke palpitations or arrhythmia in susceptible patients.
What this interaction means in plain words
Phendimetrazine 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 effects, direct alpha-agonism from phenylephrine plus indirect norepinephrine release from phendimetrazine.
What to do
Avoid oral phenylephrine decongestants in patients taking phendimetrazine when possible. If used together, monitor blood pressure and heart rate.
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 Phendimetrazine with Phenylephrine?
MediHelp rates the interaction as moderate. Phendimetrazine 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. Phendimetrazine is a sympathomimetic anorectic and phenylephrine is a vasopressor and decongestant. Combined use can add to increases in blood pressure and heart rate and may provoke palpitations or arrhythmia in susceptible patients.
How serious is the interaction between Phendimetrazine 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: Avoid oral phenylephrine decongestants in patients taking phendimetrazine when possible. If used together, monitor blood pressure and heart rate.
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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