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Metformin was the fourth most commonly prescribed drug in the United States in 2017. In that year alone, there were over 78 million prescriptions. Considering how popular this drug is right now, it pays to know a little bit more about this medication, including how long metformin stays in your system.

 The FDA states the following information regarding metformin half-life:

Mean effective half-life: 6.2 hours 

Time to steady-state: 24 to 48 hours 

Mean accumulation ratio: 1.0

Terminal phase half-life: 6.2 hours

Metformin has an oral bioavailability of ∼50%. It is readily absorbed through the small intestine, then delivered to the liver, before finally being eliminated by the kidneys. 


What is the half-life of metformin?

Metformin has a half-life of 6.2 hours.

How long does metformin stay in your system?

Metformin is detectable in your system for the following time frames:

  • Your blood for 96.8 hours
  • Your saliva for longer than 96 hours
  • Your urine for one to four days

It is possible to get a false positive for amphetamine or methamphetamine urine test when taking metformin. 

What is the peak time of metformin?

According to the FDA, peak time for Metformin is 2 to 3 hours for immediate-release tablets and 6 to 8 hours for extended-release tablets.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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