Drug interactions
Captopril-hydrochlorothiazide + Sulfamethoxazole
Severity: Moderate
Captopril-hydrochlorothiazide and Sulfamethoxazole: moderate 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
Sulfamethoxazole is usually given with trimethoprim, which can cause hyperkalemia, and ACE inhibitors add to this risk, while thiazides can cause hyponatremia. Combined use has been associated with electrolyte disturbances, especially in older patients or those with renal impairment.
What this interaction means in plain words
Captopril-hydrochlorothiazide and Sulfamethoxazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Trimethoprim blocks epithelial sodium channels raising potassium, adding to ACE inhibitor potassium retention, while thiazide-induced sodium loss can contribute to hyponatremia.
What to do
Monitor serum potassium, sodium and creatinine within the first week or so of combination therapy, particularly in older or renally impaired patients, and consider an alternative antibiotic if abnormalities develop.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Captopril-hydrochlorothiazide
- Aliskiren + Captopril-hydrochlorothiazide Contraindicated
- Captopril-hydrochlorothiazide + Dofetilide Contraindicated
- Captopril-hydrochlorothiazide + Sacubitril / valsartan Contraindicated
- Aceclofenac + Captopril-hydrochlorothiazide Major
- Aldesleukin + Captopril-hydrochlorothiazide Major
- Amifostine + Captopril-hydrochlorothiazide Major
Frequently asked questions
Can I take Captopril-hydrochlorothiazide with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Captopril-hydrochlorothiazide and Sulfamethoxazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Sulfamethoxazole is usually given with trimethoprim, which can cause hyperkalemia, and ACE inhibitors add to this risk, while thiazides can cause hyponatremia. Combined use has been associated with electrolyte disturbances, especially in older patients or those with renal impairment.
How serious is the interaction between Captopril-hydrochlorothiazide and Sulfamethoxazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor serum potassium, sodium and creatinine within the first week or so of combination therapy, particularly in older or renally impaired patients, and consider an alternative antibiotic if abnormalities develop.
What other medicines interact with Captopril-hydrochlorothiazide?
MediHelp also lists interactions of Captopril-hydrochlorothiazide with, for example, Aliskiren, Dofetilide, Sacubitril / valsartan. The full list is on the Captopril-hydrochlorothiazide page.
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