Drug interactions
Risperidone + Trimethoprim
Severity: Moderate
Risperidone 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
Both drugs have been linked with QT prolongation, so the combination may modestly increase arrhythmia risk in susceptible patients. Trimethoprim can also cause hyperkalemia, which affects cardiac risk.
What this interaction means in plain words
Risperidone 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.
Risperidone belongs to Central Nervous System; Trimethoprim belongs to Anti Bacterial.
Why it happens
Additive effects on cardiac repolarization.
What to do
Check ECG and electrolytes in patients with other QT risk factors, and 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 Risperidone
- Ibutilide + Risperidone Contraindicated
- Risperidone + Vandetanib Contraindicated
- Adagrasib + Risperidone Major
- Amiodarone + Risperidone Major
- Amisulpride + Risperidone Major
- Amoxapine + Risperidone Major
Other interactions of Trimethoprim
Frequently asked questions
Can I take Risperidone with Trimethoprim?
MediHelp rates the interaction as moderate. Risperidone 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. Both drugs have been linked with QT prolongation, so the combination may modestly increase arrhythmia risk in susceptible patients. Trimethoprim can also cause hyperkalemia, which affects cardiac risk.
How serious is the interaction between Risperidone 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 electrolytes in patients with other QT risk factors, and consider an alternative antibiotic if QTc is prolonged.
What other medicines interact with Risperidone?
MediHelp also lists interactions of Risperidone with, for example, Ibutilide, Vandetanib, Adagrasib. The full list is on the Risperidone page.
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