Drug interactions
Norepinephrine + Promethazine
Severity: Moderate
Norepinephrine and Promethazine: 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
Promethazine has alpha-adrenergic blocking activity that may blunt the vasopressor response to norepinephrine. Phenothiazines can also sensitize the myocardium and prolong QT, so arrhythmias are a theoretical concern in critically ill patients receiving a vasopressor.
What this interaction means in plain words
Norepinephrine and Promethazine 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
Pharmacodynamic antagonism at alpha-adrenergic receptors, with possible additive proarrhythmic effects.
What to do
Monitor blood pressure and ECG continuously during norepinephrine infusion and titrate the vasopressor to effect. Avoid giving promethazine to hemodynamically unstable patients when alternatives exist.
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 Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Norepinephrine with Promethazine?
MediHelp rates the interaction as moderate. Norepinephrine and Promethazine 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. Promethazine has alpha-adrenergic blocking activity that may blunt the vasopressor response to norepinephrine. Phenothiazines can also sensitize the myocardium and prolong QT, so arrhythmias are a theoretical concern in critically ill patients receiving a vasopressor.
How serious is the interaction between Norepinephrine and Promethazine?
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 ECG continuously during norepinephrine infusion and titrate the vasopressor to effect. Avoid giving promethazine to hemodynamically unstable patients when alternatives exist.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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