Interferon Beta

Drug Levels and Effects:

Summary of Use during Lactation:

The levels of interferonbeta-1a in breastmilk are minuscule. In addition, because interferon is poorly absorbed orally, it is not likely to reach the bloodstream of the infant. A small number of nursing mothers receiving interferonbeta-1a while partially breastfeeding their infants and one woman exclusively breastfed her infant while taking interferonbeta-1b and reported no adverse effects. No special precautions appear to be required during breastfeeding while using interferonbeta. Holder pasteurization (62.5 degrees C for 30 minutes) decreases the concentration of endogenous interferon-gamma by an average about 10%. [1]

Drug Levels:

Maternal Levels.

Six women were receiving interferonbeta-1a (Avonex, Biogen) 30 mcg intramuscularly once weekly for multiple sclerosis. Milk samples from both breasts were collected after pumping with an electric breast pump at 8 times after a dose at baseline and at 7 other times during the first 72 hours after a dose. Samples were combined and analyzed for interferonbeta-1a. About half of the samples had undetectable (<20 ng/L) amounts of drug. The highest concentrations were found at 1 or 4 hours after the dose in all women. The highest concentration found was 171 ng/L in one woman. Using this value, the authors estimated that the maximum weight-adjusted dosage that an infant would receive is 0.006% of the maternal dose.[2]

Infant Levels.

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

Effects in Breastfed Infants:

Six women had been receiving interferonbeta-1a (Avonex, Biogen) 30 mcg intramuscularly once weekly for multiple sclerosis for months to years. None of the mothers noticed any adverse effects in their breastfed infants.[2]

A woman received interferonbeta-1b (Betaferon, BayerHealthCare; dosage unspecified) for multiple sclerosis throughout pregnancy. She continued the drug while she exclusively breastfed her infant. At 5 months of age, the infant was monitored regularly by a physician and was developing well with no abnormalities.[3]

Possible Effects on Lactation:

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

Alternate Drugs to Consider:

Glatiramer Acetate


1. Ewaschuk JB, Unger S, O'Connor DL et al. Effect of pasteurization on selected immune components of donated human breast milk. J Perinatol. 2011;31:593-8. PMID:21330996
2. Hale TW, Siddiqui AA, Baker TE. Transfer of interferonbeta-1a into human breastmilk. Breastfeed Med. 2012;7:123-5. PMID:21988602
3. Rockhoff M, Hellwig K. [Family planning and interferon (</span>beta)-1b - A case report of successful hormonal stimulation, pregnancy and breast-feeding under interferon (</span>beta)-1b]. Aktuel Neurol Suppl. 2012;39 Suppl 1:S49-S51.

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Immunologic Adjuvants

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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