Drug interactions
Enalapril-hydrochlorothiazide + Trimethoprim
Severity: Major
Enalapril-hydrochlorothiazide and Trimethoprim: major interaction.
Last updated Sources: US FDA label
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 reduces renal potassium excretion and, with an ACE inhibitor, can cause significant hyperkalemia, especially in older patients or those with renal impairment. Thiazide-induced potassium loss only partly offsets this. Severe cases and associated hospitalisations have been reported.
What this interaction means in plain words
Enalapril-hydrochlorothiazide 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-hydrochlorothiazide belongs to Cardiovascular; Trimethoprim belongs to Anti Bacterial.
Why it happens
Trimethoprim blocks the epithelial sodium channel in the distal nephron, adding to ACE inhibitor-induced aldosterone suppression.
What to do
Check potassium and creatinine within the first week of combined use, and avoid high doses and use in renal impairment. Choose an alternative antibiotic when possible.
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
Other interactions of Enalapril-hydrochlorothiazide
- Aliskiren + Enalapril-hydrochlorothiazide Contraindicated
- Dofetilide + Enalapril-hydrochlorothiazide Contraindicated
- Enalapril-hydrochlorothiazide + Protein a column Contraindicated
- Enalapril-hydrochlorothiazide + Sacubitril / valsartan Contraindicated
- Amifostine + Enalapril-hydrochlorothiazide Major
- Amiloride + Enalapril-hydrochlorothiazide Major
Other interactions of Trimethoprim
Frequently asked questions
Can I take Enalapril-hydrochlorothiazide with Trimethoprim?
MediHelp rates the interaction as major. Enalapril-hydrochlorothiazide 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 reduces renal potassium excretion and, with an ACE inhibitor, can cause significant hyperkalemia, especially in older patients or those with renal impairment. Thiazide-induced potassium loss only partly offsets this. Severe cases and associated hospitalisations have been reported.
How serious is the interaction between Enalapril-hydrochlorothiazide 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 potassium and creatinine within the first week of combined use, and avoid high doses and use in renal impairment. Choose an alternative antibiotic when possible.
What other medicines interact with Enalapril-hydrochlorothiazide?
MediHelp also lists interactions of Enalapril-hydrochlorothiazide with, for example, Aliskiren, Dofetilide, Protein a column. The full list is on the Enalapril-hydrochlorothiazide page.
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