Metformin/Trimethoprim Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, your kidneys may not be able to properly remove metformin from your blood.

What might happen:

The effects of metformin may increase and cause a serious condition called lactic acidosis. Symptoms of lactic acidosis are: feeling very weak, tired, or uncomfortable; unusual muscle pain; trouble breathing; unusual or unexpected stomach discomfort; feeling cold, dizziness or lightheadedness; or suddenly developing a slow or irregular heartbeat.

What you should do about this interaction:

Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together.Your doctor may want to adjust the dosage of your metformin, change your antibiotic, or order laboratory tests to monitor your condition while you are on this combination.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this drug interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Glucophage (metformin hydrochloride) US prescribing information. Bristol-Myers Squibb Company May, 2018.
  • 2.Muller F, Konig J, Glaeser H, Schmidt I, Zolk O, Fromm MF, Maas R. Molecular mechanism of renal tubular secretion of the antimalarial drug chloroquine. Antimicrob Agents Chemother 2011 Jul;55(7):3091-8.
  • 3.Muller F, Pontones CA, Renner B, Mieth M, Hoier E, Auge D, Maas R, Zolk O, Fromm MF. N(1)-methylnicotinamide as an endogenous probe for drug interactions by renal cation transporters: studies on the metformin-trimethoprim interaction. Eur J Clin Pharmacol 2015 Jan; 71(1):85-94.
  • 4.Grun B, Kiessling MK, Burhenne J, Riedel KD, Weiss J, Rauch G, Haefeli WE, Czock D. Trimethoprim-metformin interaction and its genetic modulation by OCT2 and MATE1 transporters. Br J Clin Pharmacol 2013 Nov;76(5):787-96.
  • 5.Vecchio S, Giampreti A, Petrolini VM, Lonati D, Protti A, Papa P, Rognoni C, Valli A, Rocchi L, Rolandi L, Manzo L, Locatelli CA. Metformin accumulation: lactic acidosis and high plasmatic metformin levels in a retrospective case series of 66 patients on chronic therapy. Clin Toxicol (Phila) 2014 Feb;52(2):129-35.

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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.