Drug interactions
Fluphenazine + Trimethoprim
Severity: Moderate
Fluphenazine and Trimethoprim: 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
Fluphenazine prolongs the QT interval, and trimethoprim has been linked to rare QT prolongation or hyperkalemia that may contribute to arrhythmia. The combined risk is generally low but relevant in susceptible patients.
What this interaction means in plain words
Fluphenazine and Trimethoprim 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.
Fluphenazine belongs to Central Nervous System; Trimethoprim belongs to Anti Bacterial.
Why it happens
Possible additive QTc prolongation; trimethoprim's effect is weak and not well characterized.
What to do
Monitor ECG and potassium in patients with cardiac disease or other QT-prolonging drugs. Consider an alternative antibiotic if QTc is prolonged.
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 Fluphenazine
- Arsenic trioxide + Fluphenazine Contraindicated
- Dofetilide + Fluphenazine Contraindicated
- Fluphenazine + Ibutilide Contraindicated
- Fluphenazine + Pimozide Contraindicated
- Adagrasib + Fluphenazine Major
- Alfentanil + Fluphenazine Major
Other interactions of Trimethoprim
Frequently asked questions
Can I take Fluphenazine with Trimethoprim?
MediHelp rates the interaction as moderate. Fluphenazine and Trimethoprim 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. Fluphenazine prolongs the QT interval, and trimethoprim has been linked to rare QT prolongation or hyperkalemia that may contribute to arrhythmia. The combined risk is generally low but relevant in susceptible patients.
How serious is the interaction between Fluphenazine and Trimethoprim?
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 ECG and potassium in patients with cardiac disease or other QT-prolonging drugs. Consider an alternative antibiotic if QTc is prolonged.
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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