Drug interactions
Chlorpromazine + Sulfamethoxazole
Severity: Moderate
Chlorpromazine 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
Sulfamethoxazole-containing antibiotics have been linked to rare QT prolongation and arrhythmia reports. Combined with chlorpromazine, the risk of QT-related arrhythmia may be somewhat increased, especially with electrolyte disturbance or heart disease.
What this interaction means in plain words
Chlorpromazine 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 QT prolongation; the effect of sulfamethoxazole on repolarization is weakly established.
What to do
Check ECG and electrolytes in patients with other QT risk factors and correct any abnormalities. Consider an alternative antibiotic in patients with known long QT.
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 Chlorpromazine
- Chlorpromazine + Dofetilide Contraindicated
- Chlorpromazine + Dronedarone Contraindicated
- Chlorpromazine + Droperidol Contraindicated
- Chlorpromazine + Ibutilide Contraindicated
- Chlorpromazine + Metrizamide Contraindicated
- Chlorpromazine + Panobinostat Contraindicated
Frequently asked questions
Can I take Chlorpromazine with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Chlorpromazine 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. Sulfamethoxazole-containing antibiotics have been linked to rare QT prolongation and arrhythmia reports. Combined with chlorpromazine, the risk of QT-related arrhythmia may be somewhat increased, especially with electrolyte disturbance or heart disease.
How serious is the interaction between Chlorpromazine 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: Check ECG and electrolytes in patients with other QT risk factors and correct any abnormalities. Consider an alternative antibiotic in patients with known long QT.
What other medicines interact with Chlorpromazine?
MediHelp also lists interactions of Chlorpromazine with, for example, Dofetilide, Dronedarone, Droperidol. The full list is on the Chlorpromazine page.
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