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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: November 15, 2023.

Estimated reading time: 2 minutes

CASRN: 242138-07-4

Drug Levels and Effects

Summary of Use during Lactation

Preliminary evidence indicates that the amount in milk is 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] Many infants have been breastfed during maternal omalizumab therapy, with no increase in infectious complications. Omalizumab is considered acceptable to use during breastfeeding.[2,3] Waiting for at least 2 weeks postpartum to resume therapy may minimize transfer to the infant.[4]

Drug Levels

Maternal Levels. A woman received omalizumab 5 weekly doses of omalizumab 150 mg subcutaneously during pregnancy until 28 weeks of gestation. Breastmilk omalizumab levels were determined on days 4 and 5 postpartum, which were 85 and 86 days after the last dose of omalizumab. Four concentrations in milk were below 2 mcg/L and one was just over 8 mcg/L.[5]

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

Effects in Breastfed Infants

A manufacturer-based omalizumab pregnancy registry has followed pregnant and nursing mothers for several years. Of 230 infants followed, 154 were breastfed while their mothers were taking omalizumab. Another 32 were breastfed without being exposed to the drug in milk and 44 were not breastfed. No difference in serious adverse events were seen among the three groups of infants. Infections occurred at a similar rate in all groups.[6]

Several case reports of infants being breastfed during maternal omalizumab therapy have been published. No adverse effects have been found.[7-11]

A woman with cystic fibrosis and severe, persistent asthma was started on omalizumab 600 mg subcutaneously every 2 weeks. She was maintained on this regimen for 5 years when she became pregnant. The regimen was continued during pregnancy and postpartum. She breastfed (extent not stated) for 8 months. At 10 months of age, her infant was in good health.[12]

Effects on Lactation and Breastmilk

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

Alternate Drugs to Consider

(Asthma) Benralizumab, Mepolizumab


Anderson PO. Monoclonal antibodies during breastfeeding. Breastfeed Med 2021;16:591-3. [PubMed: 33956488]
Türk M, Carneiro-Leao L, Kolkhir P, et al. How to treat patients with chronic spontaneous urticaria with omalizumab: Questions and answers. J Allergy Clin Immunol Pract 2020;8:113-24. [PubMed: 31374358]
Middleton PG, Gade EJ, Aguilera C, et al. ERS/TSANZ Task Force Statement on the management of reproduction and pregnancy in women with airways diseases. Eur Respir J 2020;55:1901208. [PubMed: 31699837]
Krysko KM, Dobson R, Alroughani R, et al. Family planning considerations in people with multiple sclerosis. Lancet Neurol 2023;22:350-66. [PubMed: 36931808]
Saito J, Yakuwa N, Sandaiji N, et al. Omalizumab concentrations in pregnancy and lactation: A case study. J Allergy Clin Immunol Pract 2020;8:3603-4. [PubMed: 32544544]
López Leon, S, Kaufman DG, Howard M, et al. Safety outcomes among infants exposed to omalizumab via breastfeeding: Results from the Xolair Pregnancy Registry (Expect). Pharmacoepidemiol Drug Saf 2019;28 (Suppl 2):374-5. doi:10.1002/pds.4864 [CrossRef]
Ensina LF, Cusato-Ensina AP, Camelo-Nunes IC, Sole D. Omalizumab as third-line therapy for urticaria during pregnancy. J Investig Allergol Clin Immunol 2017;27:326-7. [PubMed: 29057743]
González-Medina M, Curto-Barredo L, Labrador-Horrillo M, Gimenez-Arnau A. Omalizumab use during pregnancy for chronic spontaneous urticaria (CSU): Report of two cases. J Eur Acad Dermatol Venereol 2017;31:e245-6. [PubMed: 27868240]
Losappio LM, Mirone C, Schroeder JW, et al. Omalizumab use in chronic spontaneous urticaria during pregnancy and a four years' follow-up: A case report. Case Rep Dermatol 2020;12:174-7. [PMC free article: PMC7588681] [PubMed: 33173477]
Majou D, Moreira B, Martin C, et al. Safety of omalizumab during pregnancy and breast-feeding with assessment of placental transfer: A case report. Allergy Asthma Immunol Res 2021;13:515-6. [PMC free article: PMC7984957] [PubMed: 33733644]
Liao SL, Yu M, Zhao ZT, Maurer M. Case report: Omalizumab for chronic spontaneous urticaria in pregnancy. Front Immunol 2021;12:652973. [PMC free article: PMC8007859] [PubMed: 33796115]
Riberi L, Pizzimenti S, Riccardi E, et al. Beneficial effects and safety of omalizumab during pregnancy in a patient with cystic fibrosis. J Cyst Fibros 2022;21:S91. doi:10.1016/S1569-1993(22)00433-7 [CrossRef]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Milk, Human

Anti-Allergic Agents

Anti-Asthmatic Agents

Antibodies, Monoclonal

Antibodies, Anti-Idiotypic

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: NBK501801PMID: 30000860


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