Lisinopril and Sulfamethoxazole Trimethoprim: Drug Interaction Guide

Quick answer: This combination requires caution. Lisinopril and Sulfamethoxazole Trimethoprim can be used together with adjustments and monitoring.

Interaction severity: Moderate — caution required

How Lisinopril interacts with Sulfamethoxazole Trimethoprim

Trimethoprim acts like a potassium-sparing diuretic by blocking epithelial sodium channels in the distal nephron. Combined with ACE inhibition from lisinopril, this increases hyperkalemia risk.

What you should do

Check potassium and renal function soon after starting therapy, especially in older adults or patients with kidney disease. Consider an alternative antibiotic for high-risk patients.

Key facts

Severity

Moderate — caution required

Mechanism

Trimethoprim acts like a potassium-sparing diuretic by blocking epithelial sodium channels in the distal nephron. Combin...

Action

Check potassium and renal function soon after starting therapy, especially in older adults or patients with kidney disea...

Important medical disclaimer: This page provides educational information about drug interactions for general reference. It is not a substitute for professional medical advice, diagnosis, or treatment. Always discuss your specific medications with a qualified healthcare provider before starting, stopping, or changing any treatment. About our editorial team.

Frequently asked questions

Can I take Lisinopril and Sulfamethoxazole Trimethoprim together?

With caution. Check potassium and renal function soon after starting therapy, especially in older adults or patients with kidney disease. Consider an alternative antibiotic for high-risk patients.

What is the severity of this interaction?

The interaction between Lisinopril and Sulfamethoxazole Trimethoprim is classified as Moderate — caution required. Trimethoprim acts like a potassium-sparing diuretic by blocking epithelial sodium channels in the distal nephron. Combined with ACE inhibition from lisinopril, this increases hyperkalemia risk.

What should I do if I'm prescribed both?

Check potassium and renal function soon after starting therapy, especially in older adults or patients with kidney disease. Consider an alternative antibiotic for high-risk patients. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

Last reviewed: by iMedic Medical Editorial Team. Our editorial process.