Drug interactions
Erythromycin base + Fluphenazine
Severity: Major
Erythromycin base and Fluphenazine: major 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
Erythromycin prolongs the QT interval and may increase the risk of torsades de pointes when added to fluphenazine. The risk is greater with electrolyte disturbances or underlying heart disease.
What this interaction means in plain words
Erythromycin base and Fluphenazine 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.
Why it happens
Additive QT prolongation; erythromycin may also modestly raise phenothiazine levels via CYP3A4 inhibition.
What to do
Use a non-QT-prolonging antibiotic such as amoxicillin where suitable; otherwise check a baseline ECG, correct potassium and magnesium, and monitor QTc.
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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Other interactions of Fluphenazine
- Arsenic trioxide + Fluphenazine Contraindicated
- Dofetilide + Fluphenazine Contraindicated
- Fluphenazine + Ibutilide Contraindicated
- Fluphenazine + Pimozide Contraindicated
- Adagrasib + Fluphenazine Major
- Alfentanil + Fluphenazine Major
Frequently asked questions
Can I take Erythromycin base with Fluphenazine?
MediHelp rates the interaction as major. Erythromycin base and Fluphenazine 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. Erythromycin prolongs the QT interval and may increase the risk of torsades de pointes when added to fluphenazine. The risk is greater with electrolyte disturbances or underlying heart disease.
How serious is the interaction between Erythromycin base and Fluphenazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use a non-QT-prolonging antibiotic such as amoxicillin where suitable; otherwise check a baseline ECG, correct potassium and magnesium, and monitor QTc.
What other medicines interact with Fluphenazine?
MediHelp also lists interactions of Fluphenazine with, for example, Arsenic trioxide, Dofetilide, Ibutilide. The full list is on the Fluphenazine page.
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