Drug interactions
Irbesartan + Trimethoprim
Severity: Major
Irbesartan and Trimethoprim: major interaction.
Last updated Sources: UK SmPC
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 reduce renal potassium excretion, so combined use can cause clinically important hyperkalemia. Risk is higher with high-dose trimethoprim, renal impairment, diabetes, advanced age or other potassium-raising drugs.
What this interaction means in plain words
Irbesartan and Trimethoprim 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.
Irbesartan belongs to Cardiovascular; Trimethoprim belongs to Anti Bacterial.
Why it happens
Trimethoprim blocks epithelial sodium channels in the distal nephron in an amiloride-like way, and irbesartan lowers aldosterone-mediated potassium excretion, producing additive potassium retention.
What to do
Check serum potassium and creatinine within several days of starting trimethoprim and repeat as needed. Choose an alternative antibiotic in patients with renal impairment or other hyperkalemia risks.
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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References
- Aprovel 150mg film-coated tablets - SmPC sections 4.3/4.5 (class statement: other medicinal products that may increase serum potassium levels; "concomitant use of potassium-sparing diuretics, potassium supplements, salt substitutes containing potassium or other medicinal products that may increase… — electronic medicines compendium (UK SmPC)
Other interactions of Irbesartan
- Aliskiren + Irbesartan Contraindicated
- Irbesartan + Sparsentan Contraindicated
- Amifostine + Irbesartan Major
- Amiloride + Irbesartan Major
- Amlodipine-benazepril + Irbesartan Major
- Amlodipine-hydrochlorothiazide-valsartan + Irbesartan Major
Other interactions of Trimethoprim
Frequently asked questions
Can I take Irbesartan with Trimethoprim?
MediHelp rates the interaction as major. Irbesartan and Trimethoprim 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 reduce renal potassium excretion, so combined use can cause clinically important hyperkalemia. Risk is higher with high-dose trimethoprim, renal impairment, diabetes, advanced age or other potassium-raising drugs.
How serious is the interaction between Irbesartan and Trimethoprim?
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 several days of starting trimethoprim and repeat as needed. Choose an alternative antibiotic in patients with renal impairment or other hyperkalemia risks.
What other medicines interact with Irbesartan?
MediHelp also lists interactions of Irbesartan with, for example, Aliskiren, Sparsentan, Amifostine. The full list is on the Irbesartan page.
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