Last update: March 22, 2018

Metformin Hydrochloride

Very Low Risk for breastfeeding

Safe. Compatible.
Minimal risk for breastfeeding and infant.

Oral antidiabetic medication used for treatment of Diabetes Type II, Obesity and Polycystic Ovarian Syndrome (PCOS). Biguanide drugs act by decreasing Neoglycogenesis (new formation of sugar) in the liver. Low risk of Hypoglycemia.

Metformin is excreted into breast milk in non-significant amount and without harmful effect on breastfed infants of treated mothers,

Obesity is associated with breastfeeding difficulties. In spite of Metformin has beneficial effect on Obesity, this is not true with PCOS because lactation capacity is related to growth of breast tissue during pregnancy which is not improved by the use of Metformin,

Oral antidiabetic drugs are not effective for Diabetes Type I. For Diabetes Type II diet, physical exercise and breastfeeding may ameliorate glycemia levels. See remarks on mother's Diabetes Mellitus by consulting specific item.


We do not have alternatives for Metformin Hydrochloride since it is relatively safe.

Suggestions made at e-lactancia are done by APILAM´s pediatricians and pharmacists, and are based on updated scientific publications.
It is not intended to replace the relationship you have with your doctor but to compound it.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Metformin Hydrochloride in other languages or writings:


Metformin Hydrochloride belongs to this group or family:


Main tradenames from several countries containing Metformin Hydrochloride in its composition:


Variable Value Unit
Oral Bioavail. 50 - 60 %
Molecular weight 166 daltons
Protein Binding 0 %
VD 0,9 - 3,9 l/Kg
Tmax 2,5 hours
T1/2 6,5 hours
M/P ratio 0,4 - 0,6 -
Theoretical Dose 0,04 mg/Kg/d
Relative Dose 1,1 %


  1. Serrano Aguayo P, García de Quirós Muñoz JM, Bretón Lesmes I, Cózar León MV. Tratamiento de enfermedades endocrinológicas durante la lactancia. [Endocrinologic diseases management during breastfeeding.] Med Clin (Barc). 2015 Abstract
  2. Rowe H, Baker T, Hale TW. Maternal medication, drug use, and breastfeeding. Pediatr Clin North Am. 2013 Feb;60(1):275-94. Abstract
  3. Vanky E, Nordskar JJ, Leithe H, Hjorth-Hansen AK, Martinussen M, Carlsen SM. Breast size increment during pregnancy and breastfeeding in mothers with polycystic ovary syndrome: a follow-up study of a randomised controlled trial on metformin versus placebo. BJOG. 2012 Abstract Full text (link to original source) Full text (in our servers)
  4. Cicero AF, Tartagni E, Ertek S. Metformin and its clinical use: new insights for an old drug in clinical practice. Arch Med Sci. 2012 Abstract Full text (link to original source) Full text (in our servers)
  5. Refuerzo JS. Oral hypoglycemic agents in pregnancy. Obstet Gynecol Clin North Am. 2011 Abstract
  6. Amir LH, Pirotta MV, Raval M. Breastfeeding--evidence based guidelines for the use of medicines. Aust Fam Physician. 2011 Sep;40(9):684-90. Review. Abstract Full text (link to original source) Full text (in our servers)
  7. Eyal S, Easterling TR, Carr D, Umans JG, Miodovnik M, Hankins GD, Clark SM, Risler L, Wang J, Kelly EJ, Shen DD, Hebert MF. Pharmacokinetics of metformin during pregnancy. Drug Metab Dispos. 2010 Abstract Full text (link to original source) Full text (in our servers)
  8. Glatstein MM, Djokanovic N, Garcia-Bournissen F, Finkelstein Y, Koren G. Use of hypoglycemic drugs during lactation. Can Fam Physician. 2009 Abstract Full text (link to original source) Full text (in our servers)
  9. Goldenberg N, Glueck C. Medical therapy in women with polycystic ovarian syndrome before and during pregnancy and lactation. Minerva Ginecol. 2008 Abstract
  10. Gardiner SJ, Kirkpatrick CM, Zhang M, Begg EJ. Cimetidine does not appear to influence the distribution of metformin into human milk. Br J Clin Pharmacol. 2008 Abstract Full text (link to original source) Full text (in our servers)
  11. Feig DS, Briggs GG, Koren G. Oral antidiabetic agents in pregnancy and lactation: a paradigm shift? Ann Pharmacother. 2007 Abstract
  12. Glueck CJ, Wang P. Metformin before and during pregnancy and lactation in polycystic ovary syndrome. Expert Opin Drug Saf. 2007 Abstract
  13. Thatcher SS, Jackson EM. Pregnancy outcome in infertile patients with polycystic ovary syndrome who were treated with metformin. Fertil Steril. 2006 Abstract
  14. Glueck CJ, Salehi M, Sieve L, Wang P. Growth, motor, and social development in breast- and formula-fed infants of metformin-treated women with polycystic ovary syndrome. J Pediatr. 2006 Abstract
  15. Briggs GG, Ambrose PJ, Nageotte MP, Padilla G, Wan S. Excretion of metformin into breast milk and the effect on nursing infants. Obstet Gynecol. 2005 Abstract
  16. Hale T, Kristensen J, Hackett L, Kohan R, Ilett K. Transfer of metformin into human milk. Adv Exp Med Biol. 2004 Abstract
  17. Gardiner SJ, Kirkpatrick CM, Begg EJ, Zhang M, Moore MP, Saville DJ. Transfer of metformin into human milk. Clin Pharmacol Ther. 2003 Abstract Full text (link to original source) Full text (in our servers)
  18. Hale TW, Kristensen JH, Hackett LP, Kohan R, Ilett KF. Transfer of metformin into human milk. Diabetologia. 2002 Abstract Full text (link to original source) Full text (in our servers)

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