Drug interactions
Enalapril + Trimethoprim
Severity: Major
Enalapril and Trimethoprim: 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
Trimethoprim blocks epithelial sodium channels in the distal nephron, reducing potassium excretion, and enalapril lowers aldosterone. Together they can cause clinically significant hyperkalemia, especially in older patients, those with renal impairment, or on high-dose trimethoprim.
What this interaction means in plain words
Enalapril 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.
Enalapril belongs to Cardiovascular; Trimethoprim belongs to Anti Bacterial.
Why it happens
Additive reduction of renal potassium excretion through ENaC blockade (trimethoprim) and decreased aldosterone (ACE inhibitor).
What to do
Check serum potassium and creatinine within several days of starting trimethoprim and consider an alternative antibiotic in high-risk patients. Avoid additional potassium-raising agents.
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 Enalapril
- Aliskiren + Enalapril Contraindicated
- Enalapril + Protein a column Contraindicated
- Enalapril + Sacubitril / valsartan Contraindicated
- Enalapril + Sacubitril-valsartan Contraindicated
- Amifostine + Enalapril Major
- Amiloride + Enalapril Major
Other interactions of Trimethoprim
Frequently asked questions
Can I take Enalapril with Trimethoprim?
MediHelp rates the interaction as major. Enalapril 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. Trimethoprim blocks epithelial sodium channels in the distal nephron, reducing potassium excretion, and enalapril lowers aldosterone. Together they can cause clinically significant hyperkalemia, especially in older patients, those with renal impairment, or on high-dose trimethoprim.
How serious is the interaction between Enalapril 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 consider an alternative antibiotic in high-risk patients. Avoid additional potassium-raising agents.
What other medicines interact with Enalapril?
MediHelp also lists interactions of Enalapril with, for example, Aliskiren, Protein a column, Sacubitril / valsartan. The full list is on the Enalapril page.
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