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Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.

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Drugs and Lactation Database (LactMed®) [Internet].

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Last Revision: December 15, 2023.

Estimated reading time: 1 minute

CASRN: 679818-59-8

Drug Levels and Effects

Summary of Use during Lactation

Minimal information on the clinical use of ofatumumab during breastfeeding indicates that the drug has no effect on the immunity of the infants. Because ofatumumab is a large protein molecule with a molecular weight of 149,000 Da, the amount in milk is likely to be very low.[1] It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal.[2] Ofatumumab appears to be acceptable to use during breastfeeding.[3] Breastfeeding can resume after the injection; however, waiting for at least 2 weeks postpartum to resume therapy may minimize transfer to the infant.[4]

Drug Levels

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

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

Effects in Breastfed Infants

Exposure of two infants to ofatumumab in breastmilk when their mothers were being treated for multiple sclerosis caused no effect on their infants’ B-cell counts.[5]

The German Multiple Sclerosis and Pregnancy Registry reported 4 cases with of mothers who were taking ofatumumab while breastfeeding. No infant B-cell counts taken between 13 and 190 days after initiation of exposed breastfeeding showed values below the lower limit.[6]

Effects on Lactation and Breastmilk

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


Stratigakis A, Paty D, Zou P, et al. A regression approach for assessing large molecular drug concentration in breast milk. Reprod Breed 2023;3:199-207. doi:10.1016/j.repbre.2023.10.003 [CrossRef]
Anderson PO. Monoclonal antibodies during breastfeeding. Breastfeed Med 2021;16:591-3. [PubMed: 33956488]
Dobson R, Rog D, Ovadia C, et al. Anti-CD20 therapies in pregnancy and breast feeding: A review and ABN guidelines. Pract Neurol 2022;23:6-14. [PubMed: 35803727]
Krysko KM, Dobson R, Alroughani R, et al. Family planning considerations in people with multiple sclerosis. Lancet Neurol 2023;22:350-66. [PubMed: 36931808]
Schwake C, Steinle J, Thiel S, et al. Effects of anti-CD20 therapies on infant health and physiological B-cell development if administered before or during pregnancy and/or lactation. Mult Scler J 2022;28 (3 Suppl):29-30. doi:10.1177/13524585221123 [CrossRef]
Ciplea A, Witt L, Thiel S, et al. Ofatumumab in breast milk of multiple sclerosis patients. Mult Scler J 2023;29 (3_Suppl):132-3. doi:10.1177/1352458523 [CrossRef]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Milk, Human

Antibodies, Monoclonal

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.

Copyright Notice

Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.

Bookshelf ID: NBK500586PMID: 29999646


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