Spironolactone and Sulfamethoxazole Trimethoprim: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Spironolactone and Sulfamethoxazole Trimethoprim unless specifically directed by your doctor.
How Spironolactone interacts with Sulfamethoxazole Trimethoprim
Trimethoprim blocks epithelial sodium channels in the distal nephron in an amiloride-like manner, adding to spironolactone-induced potassium retention.
What you should do
Avoid the combination, particularly in older adults or patients with renal impairment. Choose an alternative antibiotic and urgently monitor potassium if exposure occurs.
Key facts
Severity
Major — avoid combination
Mechanism
Trimethoprim blocks epithelial sodium channels in the distal nephron in an amiloride-like manner, adding to spironolacto...
Action
Avoid the combination, particularly in older adults or patients with renal impairment. Choose an alternative antibiotic ...
Frequently asked questions
Can I take Spironolactone and Sulfamethoxazole Trimethoprim together?
No — this combination should generally be avoided. Avoid the combination, particularly in older adults or patients with renal impairment. Choose an alternative antibiotic and urgently monitor potassium if exposure occurs.
What is the severity of this interaction?
The interaction between Spironolactone and Sulfamethoxazole Trimethoprim is classified as Major — avoid combination. Trimethoprim blocks epithelial sodium channels in the distal nephron in an amiloride-like manner, adding to spironolactone-induced potassium retention.
What should I do if I'm prescribed both?
Avoid the combination, particularly in older adults or patients with renal impairment. Choose an alternative antibiotic and urgently monitor potassium if exposure occurs. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.