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Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

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Drugs and Lactation Database (LactMed) [Internet].

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Iron Isomaltoside 1000

Last Revision: December 3, 2018.

Estimated reading time: 2 minutes

CASRN: 1370654-58-2

Drug Levels and Effects

Summary of Use during Lactation

Iron isomaltoside 1000 is not approved for marketing in the United States by the U.S. Food and Drug Administration, but is available in other countries. Limited data indicate that breastmilk iron is increased 3 days after an intravenous infusion of iron isomaltoside, but within the normal range. By 7 days after the dose, breastmilk iron levels were similar to that of mothers taking oral iron. Iron isomaltoside 1000 appears to be acceptable to use in nursing mothers with no special precautions required. Pasteurization of milk by the Holder method reduces the concentration of iron in milk by about 6.5%.[1]

Drug Levels

Maternal Levels. Thirty women with postpartum anemia were given intravenous iron isomaltoside 1200 mg in a single intravenous dose over 15 minutes. They were compared to 35 women with postpartum anemia who took 100 mg of oral iron once or twice daily. Breastmilk samples were taken before treatment, 3 (range 2 to 4) days and again at 7 (range 6 to 8) days after the intravenous iron dose. At the 3-day point, the average breastmilk iron concentration was 0.72 mg/L in the IV iron group and 0.4 mg/L in the oral iron group, which was significantly different. At the 7-day point, the average breastmilk iron concentration was 0.47 mg/L in the IV iron group and 0.44 mg/L in the oral iron group, which was not significantly different.[2]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

Effects on Lactation and Breastmilk

In a randomized, nonblinded study, randomly assigned to receive either a single intravenous dose of 1200 mg iron isomaltoside (n = 97) or oral iron 40 to 50 mg oral iron daily or 100 mg oral iron one or two times daily (n = 99). There was no significant difference between groups in the median time to lactogenesis, nor in the time of discontinuation of breastfeeding among those who weaned their infants.[3]

Alternate Drugs to Consider

Ferric Carboxymaltose, Iron Sucrose


Mohd-Taufek N, Cartwright D, Davies M et al. The effect of pasteurization on trace elements in donor breast milk. J Perinatol. 2016;36:897-900. [PubMed: 27253894]
Holm C, Thomsen LL, Norgaard A et al. Iron concentration in breast milk normalised within one week of a single high-dose infusion of iron in randomised controlled trial. Acta Paediatr. 2017;106:256-60. [PubMed: 27883237]
Holm C, Thomsen LL, Norgaard A et al. Single-dose intravenous iron infusion or oral iron for treatment of fatigue after postpartum haemorrhage: A randomized controlled trial. Vox Sang. 2017;112:219-28. [PubMed: 28198084]

Substance Identification

Substance Name

Iron Isomaltoside 1000

CAS Registry Number


Drug Class

  • Breast Feeding
  • Ferric Compounds
  • Hematinics

Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.


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