Drug interactions
Fluvoxamine + Trimethoprim
Severity: Minor
Fluvoxamine and Trimethoprim: minor 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 associated with QT prolongation, although the evidence for trimethoprim alone is limited. Combined use may add modest arrhythmia risk, particularly in patients with other risk factors.
What this interaction means in plain words
Fluvoxamine and Trimethoprim have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fluvoxamine belongs to Central Nervous System; Trimethoprim belongs to Anti Bacterial.
Why it happens
Possible additive effects on cardiac repolarization; the mechanism is not firmly established.
What to do
No routine action is needed in low-risk patients. Check electrolytes and consider an ECG if there are other QT risk factors such as electrolyte disturbance or heart disease.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Fluvoxamine
- Agomelatine + Fluvoxamine Contraindicated
- Alosetron + Fluvoxamine Contraindicated
- Fezolinetant + Fluvoxamine Contraindicated
- Fluvoxamine + Isocarboxazid Contraindicated
- Fluvoxamine + Mavacamten Contraindicated
- Fluvoxamine + Methylene blue Contraindicated
Other interactions of Trimethoprim
Frequently asked questions
Can I take Fluvoxamine with Trimethoprim?
MediHelp rates the interaction as minor. Fluvoxamine and Trimethoprim have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Both drugs have been associated with QT prolongation, although the evidence for trimethoprim alone is limited. Combined use may add modest arrhythmia risk, particularly in patients with other risk factors.
How serious is the interaction between Fluvoxamine and Trimethoprim?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine action is needed in low-risk patients. Check electrolytes and consider an ECG if there are other QT risk factors such as electrolyte disturbance or heart disease.
What other medicines interact with Fluvoxamine?
MediHelp also lists interactions of Fluvoxamine with, for example, Agomelatine, Alosetron, Fezolinetant. The full list is on the Fluvoxamine page.
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