Drug interactions
Promethazine + Siponimod
Severity: Moderate
Promethazine and Siponimod: 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
Siponimod can cause bradycardia and atrioventricular conduction delay, especially at initiation, and promethazine may add QT effects. The combination may increase the risk of arrhythmia in susceptible patients.
What this interaction means in plain words
Promethazine and Siponimod 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 belongs to Respiratory; Siponimod belongs to Central Nervous System.
Why it happens
Additive cardiac effects: siponimod-induced bradycardia with promethazine QT prolongation.
What to do
Obtain a baseline ECG and monitor heart rate during siponimod initiation. Consider alternatives to promethazine in patients with QT risk factors.
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
Other interactions of Siponimod
- Cladribine + Siponimod Contraindicated
- Fingolimod + Siponimod Contraindicated
- Fluconazole + Siponimod Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Siponimod Contraindicated
- Ponesimod + Siponimod Contraindicated
- Siponimod + Thioridazine Contraindicated
Frequently asked questions
Can I take Promethazine with Siponimod?
MediHelp rates the interaction as moderate. Promethazine and Siponimod 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. Siponimod can cause bradycardia and atrioventricular conduction delay, especially at initiation, and promethazine may add QT effects. The combination may increase the risk of arrhythmia in susceptible patients.
How serious is the interaction between Promethazine and Siponimod?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG and monitor heart rate during siponimod initiation. Consider alternatives to promethazine in patients with QT risk factors.
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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