Drug interactions
Levofloxacin + Promethazine
Severity: Moderate
Levofloxacin 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
Levofloxacin can prolong the QT interval and promethazine can add to this effect. The combination may increase the risk of torsades de pointes, especially in patients with cardiac disease or electrolyte disturbances.
What this interaction means in plain words
Levofloxacin 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.
Levofloxacin belongs to Anti Bacterial; Promethazine belongs to Respiratory.
Why it happens
Additive QT prolongation through cardiac potassium channel blockade.
What to do
Correct hypokalemia and hypomagnesemia and monitor ECG in patients with risk factors; consider an alternative antiemetic or antibiotic.
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 Levofloxacin
- Dronedarone + Levofloxacin Contraindicated
- Ibutilide + Levofloxacin Contraindicated
- Levofloxacin + Thioridazine Contraindicated
- Levofloxacin + Vandetanib Contraindicated
- Levofloxacin + Ziprasidone Contraindicated
- Adagrasib + Levofloxacin Major
Frequently asked questions
Can I take Levofloxacin with Promethazine?
MediHelp rates the interaction as moderate. Levofloxacin 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. Levofloxacin can prolong the QT interval and promethazine can add to this effect. The combination may increase the risk of torsades de pointes, especially in patients with cardiac disease or electrolyte disturbances.
How serious is the interaction between Levofloxacin 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: Correct hypokalemia and hypomagnesemia and monitor ECG in patients with risk factors; consider an alternative antiemetic or antibiotic.
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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