Voluntary Recall of Certain Lots of Extended-Release Metformin Formulations

  • Practice Advisory PA
  • September 2020

(Reaffirmed October 2022)

Last updated October 5, 2020

This Practice Advisory addresses the ongoing U.S. Food and Drug Administration (FDA) recall of certain extended release (ER) metformin formulations1 due to the possibility that some formulations contain amounts of nitrosodimethylamine (NDMA) above the FDA's acceptable intake limit. NDMA is a probable human carcinogen (a substance that could cause cancer). The FDA does not expect nitrosamines to cause harm when ingested at or below the acceptable intake limit levels (such low levels of nitrosamines are ingested as part of common diets) even over a long period of time (such as a 70-year lifespan). Nitrosamine impurities may increase the risk of cancer if people are exposed to them at levels above the acceptable intake limit over long periods of time, but shorter-term exposure at levels above the acceptable intake limit is not expected to lead to an increase in the risk of cancer.

Currently, only some extended release formulations have been identified as possibly containing NDMA above acceptable intake limits; the recall has not been applied to immediate release formulations.

Patients should not stop taking ER metformin until communicating with their obstetrician-gynecologist or other women's healthcare practitioner. Patients who have been prescribed ER metformin should be counseled about the potential risk and consideration of alternative management options or immediate release metformin should be considered. Clinicians are advised to periodically check the FDA's website to note if the recall extends to additional metformin formulations.

Please contact [email protected] with any questions.

This Practice Advisory was developed by the American College of Obstetricians and Gynecologists in collaboration with Alison G. Cahill, MD; Aaron B. Caughey, MD, PhD; Cynthia Gyamfi-Bannerman, MD, MSc; and Anjali J. Kaimal, MD, MAS.


  1. U.S. Food and Drug Administration. Recalls, market withdrawals, and safety alerts. Available at: Retrieved September 25, 2020.
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