Drug interactions
Trimethoprim + Valsartan
Severity: Major
Trimethoprim and Valsartan: major 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 can raise serum potassium, and together they may cause clinically important hyperkalemia. The risk is greatest with high trimethoprim doses, renal impairment, older age or additional potassium-raising drugs.
What this interaction means in plain words
Trimethoprim and Valsartan can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Trimethoprim belongs to Anti Bacterial; Valsartan belongs to Cardiovascular.
Why it happens
Valsartan reduces aldosterone-mediated potassium excretion, while trimethoprim blocks epithelial sodium channels in the distal nephron, producing an additive reduction in renal potassium excretion.
What to do
Check serum potassium and creatinine within the first week of combined therapy and periodically afterward. Prefer an alternative antibiotic in patients with renal impairment or other hyperkalemia risk factors.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Valsartan
- Aliskiren + Valsartan Contraindicated
- Sparsentan + Valsartan Contraindicated
- Aldesleukin + Valsartan Major
- Amifostine + Valsartan Major
- Amiloride + Valsartan Major
- Amlodipine-benazepril + Valsartan Major
Other interactions of Trimethoprim
Frequently asked questions
Can I take Trimethoprim with Valsartan?
MediHelp rates the interaction as major. Trimethoprim and Valsartan can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs can raise serum potassium, and together they may cause clinically important hyperkalemia. The risk is greatest with high trimethoprim doses, renal impairment, older age or additional potassium-raising drugs.
How serious is the interaction between Trimethoprim and Valsartan?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check serum potassium and creatinine within the first week of combined therapy and periodically afterward. Prefer an alternative antibiotic in patients with renal impairment or other hyperkalemia risk factors.
What other medicines interact with Valsartan?
MediHelp also lists interactions of Valsartan with, for example, Aliskiren, Sparsentan, Aldesleukin. The full list is on the Valsartan page.
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