Lisinopril and Trimethoprim: Drug Interaction Guide

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

Interaction severity: Moderate — caution required

How Lisinopril interacts with Trimethoprim

Trimethoprim reduces renal potassium excretion through an amiloride-like effect, while lisinopril reduces aldosterone-mediated potassium clearance. The combination increases hyperkalaemia risk.

What you should do

Check potassium and renal function soon after initiation, especially in older adults or renal impairment. Consider an alternative antibiotic in high-risk patients.

Key facts

Severity

Moderate — caution required

Mechanism

Trimethoprim reduces renal potassium excretion through an amiloride-like effect, while lisinopril reduces aldosterone-me...

Action

Check potassium and renal function soon after initiation, especially in older adults or renal impairment. Consider an al...

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 Trimethoprim together?

With caution. Check potassium and renal function soon after initiation, especially in older adults or renal impairment. Consider an alternative antibiotic in high-risk patients.

What is the severity of this interaction?

The interaction between Lisinopril and Trimethoprim is classified as Moderate — caution required. Trimethoprim reduces renal potassium excretion through an amiloride-like effect, while lisinopril reduces aldosterone-mediated potassium clearance. The combination increases hyperkalaemia risk.

What should I do if I'm prescribed both?

Check potassium and renal function soon after initiation, especially in older adults or renal impairment. Consider an alternative antibiotic in 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.