Drug interactions
Moxifloxacin + Promethazine
Severity: Major
Moxifloxacin and Promethazine: major interaction.
Last updated Sources: Base de donnees publique des medicaments (France)
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
Moxifloxacin is a fluoroquinolone with a well-recognized QT-prolonging effect, and promethazine can add to it. The combination may increase the risk of torsades de pointes, especially with electrolyte disturbance or cardiac disease.
What this interaction means in plain words
Moxifloxacin and Promethazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Moxifloxacin belongs to Anti Bacterial; Promethazine belongs to Respiratory.
Why it happens
Additive hERG channel blockade causing QT prolongation.
What to do
Avoid if possible and choose a non-QT-prolonging antibiotic or antiemetic. If co-administered, monitor ECG and correct potassium and magnesium.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Promethazine
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
Other interactions of Moxifloxacin
- Amiodarone + Moxifloxacin Contraindicated
- Arsenic trioxide + Moxifloxacin Contraindicated
- Disopyramide + Moxifloxacin Contraindicated
- Dofetilide + Moxifloxacin Contraindicated
- Dronedarone + Moxifloxacin Contraindicated
- Droperidol + Moxifloxacin Contraindicated
Frequently asked questions
Can I take Moxifloxacin with Promethazine?
MediHelp rates the interaction as major. Moxifloxacin and Promethazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Moxifloxacin is a fluoroquinolone with a well-recognized QT-prolonging effect, and promethazine can add to it. The combination may increase the risk of torsades de pointes, especially with electrolyte disturbance or cardiac disease.
How serious is the interaction between Moxifloxacin and Promethazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid if possible and choose a non-QT-prolonging antibiotic or antiemetic. If co-administered, monitor ECG and correct potassium and magnesium.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Cabergoline, Dopamine, Ibutilide. The full list is on the Promethazine page.
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