Losartan and Trimethoprim: Drug Interaction Guide

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

Interaction severity: Moderate — caution required

How Losartan interacts with Trimethoprim

Trimethoprim blocks the renal epithelial sodium channel and inhibits potassium excretion, adding to the hyperkalaemic effect of ARBs.

What you should do

Check serum potassium and renal function within 5–7 days, particularly in elderly or renally impaired patients.

Key facts

Severity

Moderate — caution required

Mechanism

Trimethoprim blocks the renal epithelial sodium channel and inhibits potassium excretion, adding to the hyperkalaemic ef...

Action

Check serum potassium and renal function within 5–7 days, particularly in elderly or renally impaired patients.

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 Losartan and Trimethoprim together?

With caution. Check serum potassium and renal function within 5–7 days, particularly in elderly or renally impaired patients.

What is the severity of this interaction?

The interaction between Losartan and Trimethoprim is classified as Moderate — caution required. Trimethoprim blocks the renal epithelial sodium channel and inhibits potassium excretion, adding to the hyperkalaemic effect of ARBs.

What should I do if I'm prescribed both?

Check serum potassium and renal function within 5–7 days, particularly in elderly or renally impaired 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.