Metformin and Trimethoprim: Drug Interaction Guide
Quick answer: This combination requires caution. Metformin and Trimethoprim can be used together with adjustments and monitoring.
How Metformin interacts with Trimethoprim
Trimethoprim inhibits the renal organic cation transporter OCT2 and MATE1, reducing tubular secretion of metformin and increasing plasma levels with risk of lactic acidosis in CKD.
What you should do
In patients with eGFR <45 mL/min/1.73 m² consider temporarily reducing or holding metformin during trimethoprim courses; monitor renal function.
Key facts
Severity
Moderate — caution required
Mechanism
Trimethoprim inhibits the renal organic cation transporter OCT2 and MATE1, reducing tubular secretion of metformin and i...
Action
In patients with eGFR <45 mL/min/1.73 m² consider temporarily reducing or holding metformin during trimethoprim courses;...
Frequently asked questions
Can I take Metformin and Trimethoprim together?
With caution. In patients with eGFR <45 mL/min/1.73 m² consider temporarily reducing or holding metformin during trimethoprim courses; monitor renal function.
What is the severity of this interaction?
The interaction between Metformin and Trimethoprim is classified as Moderate — caution required. Trimethoprim inhibits the renal organic cation transporter OCT2 and MATE1, reducing tubular secretion of metformin and increasing plasma levels with risk of lactic acidosis in CKD.
What should I do if I'm prescribed both?
In patients with eGFR <45 mL/min/1.73 m² consider temporarily reducing or holding metformin during trimethoprim courses; monitor renal function. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.