Drug interactions
Promazine + Pseudoephedrine
Severity: Moderate
Promazine 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
Pseudoephedrine is a sympathomimetic that can increase heart rate and blood pressure, while promazine is a phenothiazine with QT-prolonging and proarrhythmic potential. Together they may raise the risk of ventricular arrhythmias in predisposed patients. Promazine also has alpha-blocking effects that may blunt pressor responses.
What this interaction means in plain words
Promazine 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
Additive cardiac effects: sympathomimetic stimulation combined with phenothiazine-related QT prolongation; the exact mechanism is not fully established.
What to do
Avoid pseudoephedrine in patients with QT risk factors, structural heart disease or electrolyte disturbance who take promazine. Obtain an ECG and monitor for palpitations or syncope if combined use is necessary.
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 Promazine with Pseudoephedrine?
MediHelp rates the interaction as moderate. Promazine 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. Pseudoephedrine is a sympathomimetic that can increase heart rate and blood pressure, while promazine is a phenothiazine with QT-prolonging and proarrhythmic potential. Together they may raise the risk of ventricular arrhythmias in predisposed patients. Promazine also has alpha-blocking effects that may blunt pressor responses.
How serious is the interaction between Promazine 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 pseudoephedrine in patients with QT risk factors, structural heart disease or electrolyte disturbance who take promazine. Obtain an ECG and monitor for palpitations or syncope if combined use is necessary.
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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