Drug interactions
Fosinopril-hydrochlorothiazide + Sulfamethoxazole
Severity: Moderate
Fosinopril-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 blocks epithelial sodium channels and can cause hyperkalemia, an effect heightened by ACE inhibitors. Thiazides can add to hyponatremia, and thrombocytopenia has been reported with thiazide plus sulfonamide combinations.
What this interaction means in plain words
Fosinopril-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
Additive effects on potassium and sodium handling (trimethoprim ENaC blockade, ACE inhibitor aldosterone reduction, thiazide natriuresis).
What to do
Monitor serum potassium, sodium and creatinine within the first week of co-trimoxazole therapy, especially in older patients or those with renal impairment.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fosinopril-hydrochlorothiazide and Sulfamethoxazole, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Fosinopril-hydrochlorothiazide
- Aliskiren + Fosinopril-hydrochlorothiazide Contraindicated
- Dofetilide + Fosinopril-hydrochlorothiazide Contraindicated
- Fosinopril-hydrochlorothiazide + Protein a column Contraindicated
- Fosinopril-hydrochlorothiazide + Sacubitril / valsartan Contraindicated
- Aldesleukin + Fosinopril-hydrochlorothiazide Major
- Amifostine + Fosinopril-hydrochlorothiazide Major
Frequently asked questions
Can I take Fosinopril-hydrochlorothiazide with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Fosinopril-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 blocks epithelial sodium channels and can cause hyperkalemia, an effect heightened by ACE inhibitors. Thiazides can add to hyponatremia, and thrombocytopenia has been reported with thiazide plus sulfonamide combinations.
How serious is the interaction between Fosinopril-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 of co-trimoxazole therapy, especially in older patients or those with renal impairment.
What other medicines interact with Fosinopril-hydrochlorothiazide?
MediHelp also lists interactions of Fosinopril-hydrochlorothiazide with, for example, Aliskiren, Dofetilide, Protein a column. The full list is on the Fosinopril-hydrochlorothiazide page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
