Drug interactions
Benzphetamine + Phenylephrine
Severity: Moderate
Benzphetamine 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
Benzphetamine is a sympathomimetic anorectic. Combined with phenylephrine, pressor effects may be additive, causing hypertension, tachycardia and arrhythmia.
What this interaction means in plain words
Benzphetamine 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: benzphetamine releases catecholamines and phenylephrine directly stimulates alpha-1 receptors.
What to do
Monitor blood pressure and heart rate and avoid systemic phenylephrine in patients with hypertension or heart disease.
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 Benzphetamine with Phenylephrine?
MediHelp rates the interaction as moderate. Benzphetamine 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. Benzphetamine is a sympathomimetic anorectic. Combined with phenylephrine, pressor effects may be additive, causing hypertension, tachycardia and arrhythmia.
How serious is the interaction between Benzphetamine 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 and avoid systemic phenylephrine in patients with hypertension or heart disease.
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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