Drug interactions
Chlorpromazine + Trimethoprim
Severity: Moderate
Chlorpromazine 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
Trimethoprim has been associated with infrequent QT prolongation and can raise potassium, which may add to arrhythmia risk. Combined with chlorpromazine, the QT effect may be additive in susceptible patients.
What this interaction means in plain words
Chlorpromazine 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.
Chlorpromazine belongs to Central Nervous System; Trimethoprim belongs to Anti Bacterial.
Why it happens
Possible additive QT prolongation; trimethoprim-induced hyperkalemia may also alter arrhythmic risk.
What to do
Check ECG and potassium in patients with additional risk factors such as renal impairment, heart disease or other QT-prolonging drugs. Choose an alternative antibiotic if QTc is markedly 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 Chlorpromazine
- Chlorpromazine + Dofetilide Contraindicated
- Chlorpromazine + Dronedarone Contraindicated
- Chlorpromazine + Droperidol Contraindicated
- Chlorpromazine + Ibutilide Contraindicated
- Chlorpromazine + Metrizamide Contraindicated
- Chlorpromazine + Panobinostat Contraindicated
Other interactions of Trimethoprim
Frequently asked questions
Can I take Chlorpromazine with Trimethoprim?
MediHelp rates the interaction as moderate. Chlorpromazine 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. Trimethoprim has been associated with infrequent QT prolongation and can raise potassium, which may add to arrhythmia risk. Combined with chlorpromazine, the QT effect may be additive in susceptible patients.
How serious is the interaction between Chlorpromazine 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: Check ECG and potassium in patients with additional risk factors such as renal impairment, heart disease or other QT-prolonging drugs. Choose an alternative antibiotic if QTc is markedly prolonged.
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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