Ramipril and Trimethoprim Sulfamethoxazole: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Ramipril and Trimethoprim Sulfamethoxazole unless specifically directed by your doctor.
How Ramipril interacts with Trimethoprim Sulfamethoxazole
Trimethoprim blocks renal epithelial sodium channels (amiloride-like effect) and ACE inhibition lowers aldosterone, causing severe hyperkalaemia and sudden death in the elderly.
What you should do
Avoid in patients over 65, renal impairment, or on potassium supplements. Prefer nitrofurantoin or amoxicillin for UTI; if unavoidable, check potassium after 3-5 days.
Key facts
Severity
Major — avoid combination
Mechanism
Trimethoprim blocks renal epithelial sodium channels (amiloride-like effect) and ACE inhibition lowers aldosterone, caus...
Action
Avoid in patients over 65, renal impairment, or on potassium supplements. Prefer nitrofurantoin or amoxicillin for UTI; ...
Frequently asked questions
Can I take Ramipril and Trimethoprim Sulfamethoxazole together?
No — this combination should generally be avoided. Avoid in patients over 65, renal impairment, or on potassium supplements. Prefer nitrofurantoin or amoxicillin for UTI; if unavoidable, check potassium after 3-5 days.
What is the severity of this interaction?
The interaction between Ramipril and Trimethoprim Sulfamethoxazole is classified as Major — avoid combination. Trimethoprim blocks renal epithelial sodium channels (amiloride-like effect) and ACE inhibition lowers aldosterone, causing severe hyperkalaemia and sudden death in the elderly.
What should I do if I'm prescribed both?
Avoid in patients over 65, renal impairment, or on potassium supplements. Prefer nitrofurantoin or amoxicillin for UTI; if unavoidable, check potassium after 3-5 days. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.