Drug interactions
Enalapril-hydrochlorothiazide + Sulfamethoxazole
Severity: Major
Enalapril-hydrochlorothiazide and Sulfamethoxazole: 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
Sulfamethoxazole is usually combined with trimethoprim, and trimethoprim raises potassium. With enalapril this raises the risk of hyperkalemia and acute kidney injury, particularly in older patients or those with renal impairment. Thiazides also add to the risk of hyponatremia.
What this interaction means in plain words
Enalapril-hydrochlorothiazide and Sulfamethoxazole 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.
Why it happens
Trimethoprim blocks epithelial sodium channels in the distal nephron, adding to ACE inhibitor reduction of aldosterone; thiazide adds sodium loss.
What to do
Check serum potassium, sodium and creatinine within days of starting and consider an alternative antibiotic in high-risk patients.
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
Frequently asked questions
Can I take Enalapril-hydrochlorothiazide with Sulfamethoxazole?
MediHelp rates the interaction as major. Enalapril-hydrochlorothiazide and Sulfamethoxazole 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. Sulfamethoxazole is usually combined with trimethoprim, and trimethoprim raises potassium. With enalapril this raises the risk of hyperkalemia and acute kidney injury, particularly in older patients or those with renal impairment. Thiazides also add to the risk of hyponatremia.
How serious is the interaction between Enalapril-hydrochlorothiazide and Sulfamethoxazole?
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, sodium and creatinine within days of starting and consider an alternative antibiotic in high-risk patients.
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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