Sulfonylureas and Trimethoprim Sulfamethoxazole: Drug Interaction Guide

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

Interaction severity: Moderate — caution required

How Sulfonylureas interacts with Trimethoprim Sulfamethoxazole

Sulfamethoxazole inhibits CYP2C9 metabolism of sulfonylureas (especially glibenclamide and glipizide) and displaces them from plasma proteins, prolonging and intensifying hypoglycaemic effect.

What you should do

Monitor blood glucose closely during the course; consider sulfonylurea dose reduction or use of an alternative antibiotic in elderly or renally impaired patients.

Key facts

Severity

Moderate — caution required

Mechanism

Sulfamethoxazole inhibits CYP2C9 metabolism of sulfonylureas (especially glibenclamide and glipizide) and displaces them...

Action

Monitor blood glucose closely during the course; consider sulfonylurea dose reduction or use of an alternative antibioti...

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 Sulfonylureas and Trimethoprim Sulfamethoxazole together?

With caution. Monitor blood glucose closely during the course; consider sulfonylurea dose reduction or use of an alternative antibiotic in elderly or renally impaired patients.

What is the severity of this interaction?

The interaction between Sulfonylureas and Trimethoprim Sulfamethoxazole is classified as Moderate — caution required. Sulfamethoxazole inhibits CYP2C9 metabolism of sulfonylureas (especially glibenclamide and glipizide) and displaces them from plasma proteins, prolonging and intensifying hypoglycaemic effect.

What should I do if I'm prescribed both?

Monitor blood glucose closely during the course; consider sulfonylurea dose reduction or use of an alternative antibiotic 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.