Drug interactions
Sulfamethoxazole + Thioridazine
Severity: Moderate
Sulfamethoxazole and Thioridazine: 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 QT prolongation, mainly in case reports. With thioridazine the arrhythmia risk may be greater.
What this interaction means in plain words
Sulfamethoxazole and Thioridazine 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.
What to do
Consider an alternative antibiotic in patients with other QT risk factors. If used, check ECG and electrolytes.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Sulfamethoxazole with Thioridazine?
MediHelp rates the interaction as moderate. Sulfamethoxazole and Thioridazine 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 QT prolongation, mainly in case reports. With thioridazine the arrhythmia risk may be greater.
How serious is the interaction between Sulfamethoxazole and Thioridazine?
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 alternative antibiotic in patients with other QT risk factors. If used, check ECG and electrolytes.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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