Drug interactions
Fluphenazine + Sulfamethoxazole
Severity: Moderate
Fluphenazine and Sulfamethoxazole: 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 sulfamethoxazole-containing products have been associated with rare QT prolongation. Combined use adds a small but real arrhythmia risk, particularly with other risk factors.
What this interaction means in plain words
Fluphenazine and Sulfamethoxazole 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.
Why it happens
Possible additive QTc prolongation; sulfamethoxazole's contribution is weak and not well characterized.
What to do
Consider an ECG and electrolyte check in patients with other QT risk factors. Choose an alternative antibiotic if QTc is already 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
Frequently asked questions
Can I take Fluphenazine with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Fluphenazine and Sulfamethoxazole 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 sulfamethoxazole-containing products have been associated with rare QT prolongation. Combined use adds a small but real arrhythmia risk, particularly with other risk factors.
How serious is the interaction between Fluphenazine and Sulfamethoxazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider an ECG and electrolyte check in patients with other QT risk factors. Choose an alternative antibiotic if QTc is already 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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