Drug interactions
Trimethoprim + Venlafaxine
Severity: Minor
Trimethoprim and Venlafaxine: 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
Trimethoprim has been associated with QT prolongation in some reports and venlafaxine may prolong QT at high doses. The combined effect is likely small in most patients.
What this interaction means in plain words
Trimethoprim and Venlafaxine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Trimethoprim belongs to Anti Bacterial; Venlafaxine belongs to Central Nervous System.
Why it happens
Possible additive QT prolongation.
What to do
No routine action is needed in low-risk patients. Check ECG and potassium in patients with other QT risk factors or hyperkalemia risk.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Trimethoprim and Venlafaxine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Other interactions of Trimethoprim
Frequently asked questions
Can I take Trimethoprim with Venlafaxine?
MediHelp rates the interaction as minor. Trimethoprim and Venlafaxine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Trimethoprim has been associated with QT prolongation in some reports and venlafaxine may prolong QT at high doses. The combined effect is likely small in most patients.
How serious is the interaction between Trimethoprim and Venlafaxine?
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 ECG and potassium in patients with other QT risk factors or hyperkalemia risk.
What other medicines interact with Venlafaxine?
MediHelp also lists interactions of Venlafaxine with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Venlafaxine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
