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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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Last Revision: April 18, 2022.

Estimated reading time: 2 minutes

CASRN: 356547-88-1

Drug Levels and Effects

Summary of Use during Lactation

Preliminary information indicates that belimumab levels in milk are very low. It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal.[1] If belimumab is required by the mother, it is not a reason to discontinue breastfeeding.[2] Until more data become available, belimumab should be used with caution during breastfeeding, especially while nursing a newborn or preterm infant.

Belimumab is a human immunoglobulin G1 (IgG1) lambda antibody. Holder pasteurization (62.5 degrees C for 30 minutes) decreases the concentration of endogenous immunoglobulin G by up to 79%.[3,4] A study of 67 colostrum samples that underwent Holder pasteurization found that IgG amounts decreased by 34 to 40%. Specific IgG subclasses decreased by different amounts, with IgG1 activity decreasing by about 37%.[5,6] None of the studies measured IgG activity.

Drug Levels

Maternal Levels. A postpartum woman with mixed connective tissue disease was started on intravenous belimumab 520 mg (10 mg/kg) every 2 weeks for 2 doses, then 520 mg monthly as well as hydroxychloroquine 200 to 400 mg daily. Belimumab milk concentrations were 0.12 mg/L at 2 weeks after the first dose and prior to the second dose, 0.17 mg/L on the following day, and 0.12 mg/L at 7 weeks after the second dose.[7]

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

Effects in Breastfed Infants

A woman with systemic lupus erythematosus was taking belimumab (dose not stated) for 1 year when she became pregnant. She received monthly belimumab infusions during pregnancy and continued postpartum, starting at 2 weeks postpartum. She breastfed her infant (extent not stated). No infant effects were mentioned.[8]

Effects on Lactation and Breastmilk

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


Sammaritano LR, Bermas BL, Chakravarty EE, et al. 2020 American College of Rheumatology Guideline for the Management of Reproductive Health in Rheumatic and Musculoskeletal Diseases. Arthritis Rheumatol. 2020;72:529–56. [PubMed: 32090480]
Götestam Skorpen C, Hoeltzenbein M, Tincani A, et al. The EULAR points to consider for use of antirheumatic drugs before pregnancy, and during pregnancy and lactation. Ann Rheum Dis. 2016;75:795–810. [PubMed: 26888948]
Koenig A, de Albuquerque Diniz EM, Barbosa SF, et al. Immunologic factors in human milk: The effects of gestational age and pasteurization. J Hum Lact. 2005;21:439–43. [PubMed: 16280560]
Adhisivam B, Vishnu Bhat B, Rao K, et al. Effect of Holder pasteurization on macronutrients and immunoglobulin profile of pooled donor human milk. J Matern Fetal Neonatal Med. 2019;32:3016–9. [PubMed: 29587541]
Rodríguez-Camejo C, Puyol A, Fazio L, et al. Impact of Holder pasteurization on immunological properties of human breast milk over the first year of lactation. Pediatr Res. 2020;87:32–41. [PubMed: 31288249]
Rodríguez-Camejo C, Puyol A, Fazio L, et al. Antibody profile of colostrum and the effect of processing in human milk banks: Implications in immunoregulatory properties. J Hum Lact. 2018;34:137–47. [PubMed: 28586632]
Saito J, Yakuwa N, Ishizuka T, et al. Belimumab concentrations in maternal serum and breast milk during breastfeeding and the safety assessment of the infant: A case study. Breastfeed Med. 2020;15:475–7. [PMC free article: PMC7374635] [PubMed: 32326740]
Danve A, Perry L, Deodhar A. Use of belimumab throughout pregnancy to treat active systemic lupus erythematosus: A case report. Semin Arthritis Rheum. 2014;44:195–7. [PubMed: 25005336]

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.


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