Ramipril and Trimethoprim: Drug Interaction Guide

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

Interaction severity: Moderate — caution required

How Ramipril interacts with Trimethoprim

Trimethoprim blocks the epithelial sodium channel in the distal nephron (amiloride-like effect) and adds to ACE inhibitor-induced potassium retention, causing hyperkalaemia particularly in the elderly.

What you should do

Check serum potassium and creatinine before and within 5-7 days of starting trimethoprim in patients on ACE inhibitors; consider nitrofurantoin as alternative.

Key facts

Severity

Moderate — caution required

Mechanism

Trimethoprim blocks the epithelial sodium channel in the distal nephron (amiloride-like effect) and adds to ACE inhibito...

Action

Check serum potassium and creatinine before and within 5-7 days of starting trimethoprim in patients on ACE inhibitors; ...

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 Ramipril and Trimethoprim together?

With caution. Check serum potassium and creatinine before and within 5-7 days of starting trimethoprim in patients on ACE inhibitors; consider nitrofurantoin as alternative.

What is the severity of this interaction?

The interaction between Ramipril and Trimethoprim is classified as Moderate — caution required. Trimethoprim blocks the epithelial sodium channel in the distal nephron (amiloride-like effect) and adds to ACE inhibitor-induced potassium retention, causing hyperkalaemia particularly in the elderly.

What should I do if I'm prescribed both?

Check serum potassium and creatinine before and within 5-7 days of starting trimethoprim in patients on ACE inhibitors; consider nitrofurantoin as alternative. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

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