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Interferon Alfa use while Breastfeeding

Medically reviewed by Last updated on Aug 2, 2023.

Interferon Alfa Levels and Effects while Breastfeeding

Summary of Use during Lactation

Because of the low levels in milk and poor oral absorption by the infant, it is unlikely that interferon use by a nursing mother presents any serious risk to the breastfed infant.[1]

For treating maternal hepatitis B, no difference exists in infection rates between breastfed and formula-fed infants born to hepatitis B-infected women, if the infant receives hepatitis B immune globulin and hepatitis B vaccine at birth. Mothers with hepatitis B are encouraged to breastfeed their infants after their infants receive these preventative measures.[2,3]

Hepatitis C is not transmitted through breastmilk and breastmilk has been shown to inactivate hepatitis C virus (HCV).[4-7] However, the Centers for Disease Control recommends that mothers with HCV infection should consider abstaining from breastfeeding if their nipples are cracked or bleeding. It is not clear if this warning would apply to mothers who are being treated for hepatitis C.

Infants born to mothers with HCV infection should be tested for HCV infection; because maternal antibody is present for the first 18 months of life and before the infant mounts an immunologic response, nucleic acid testing is recommended.[4,7]

Drug Levels

Maternal Levels. Two mothers taking interferon alfa had milk levels measured. One mother taking 8 million units three times a week had a milk level of 1400 units/L and another taking 8 million units daily had a milk level of 6000 units/L. Both levels were apparently measured immediately postpartum (in colostrum), but the time since the previous dose was not stated.[8]

An intravenous dose of 30 million units of interferon alfa-2B in one woman resulted in a peak milk level of 1551 International Units/L which was a slight increase over two baseline levels prior to the dose which averaged 1072 International Units/L. By 12 hours after the dose, milk interferon levels were lower than baseline.[9]

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

Effects in Breastfed Infants

One infant was born to a mother who received 3 million units of interferon alfa-2a subcutaneously 3 times weekly during pregnancy and postpartum for essential thrombocytopenia. Her infant was breastfed for 2 weeks postpartum before bilateral mastitis caused the mother to terminate nursing. The infant reportedly thrived, although specific measures were not mentioned.[10]

Effects on Lactation and Breastmilk

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

Alternate Drugs to Consider

(Hepatitis B) Lamivudine, Tenofovir; (Hepatitis C) Interferon Alfacon-1, Peginterferon Alfa


Balsat M, Etienne M, Elhamri M, et al. Successful pregnancies in patients with BCR-ABL-positive leukemias treated with interferon-alpha therapy during the tyrosine kinase inhibitors era. Eur J Haematol 2018;101:774-80. [PubMed: 30179268]
Visvanathan K, Dusheiko G, Giles M, et al. Managing HBV in pregnancy. Prevention, prophylaxis, treatment and follow-up: Position paper produced by Australian, UK and New Zealand key opinion leaders. Gut 2016;65:340-50. [PubMed: 26475631]
Dionne-Odom J, Tita AT, Silverman NS. #38: Hepatitis B in pregnancy screening, treatment, and prevention of vertical transmission. Am J Obstet Gynecol 2016;214:6-14. [PubMed: 26454123]
Cottrell EB, Chou R, Wasson N, et al. Reducing risk for mother-to-infant transmission of hepatitis C virus: A systematic review for the U.S. Preventive Services Task Force. Ann Intern Med 2013;158:109-13. [PubMed: 23437438]
Pfaender S, Heyden J, Friesland M, et al. Inactivation of hepatitis C virus infectivity by human breast milk. J Infect Dis 2013;208:1943-52. [PubMed: 24068703]
Tovo PA, Calitri C, Scolfaro C, et al. Vertically acquired hepatitis C virus infection: Correlates of transmission and disease progression. World J Gastroenterol 2016;22:1382-92. [PMC free article: PMC4721973] [PubMed: 26819507]
Workowski KA, Bachmann LH, Chan PA, et al. Sexually transmitted infections treatment guidelines, 2021. MMWR Recomm Rep 2021;70:1-187. [PMC free article: PMC8344968] [PubMed: 34292926]
Haggstrom J, Adriansson M, Hybbinette T, et al. Two cases of CML treated with alpha-interferon during second and third trimester of pregnancy with analysis of the drug in the new-born immediately postpartum. Eur J Haematol 1996;57:101-2. Letter. [PubMed: 8698119]
Kumar AR, Hale TW, Mock RE. Transfer of interferon alfa into human breast milk. J Hum Lact 2000;16:226-8. [PubMed: 11153157]
Williams JM, Schlesinger PE, Gray AG. Successful treatment of essential thrombocythaemia and recurrent abortion with alpha interferon. Br J Haematol 1994;88:647-8. [PubMed: 7819084]

Substance Identification

Substance Name

Interferon Alfa

CAS Registry Number

98530-12-2; 76543-88-9; 77907-69-8

Drug Class

Breast Feeding


Milk, Human

Anti-Infective Agents

Antiviral Agents

Antineoplastic Agents

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Further information

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