Can you take filgrastim while breastfeeding?
What LactMed says
The National Library of Medicine’s own summary, quoted in full. We do not write a verdict of our own on this question, and we do not compress theirs into a label.
Filgrastim in the pharmaceutical name for granulocyte colony-stimulating factor (G-CSF). Pegfilgrastim is the long-acting form of filgrastim. Eflapegrastim and efbemalenograstim alfa are closely related G-CSF analogues. The excretion of exogenous G-CSF into breastmilk or its effects on breastfed infants have not been well studied. Limited data indicate that filgrastim and a similar G-CSF product, lenograstim, are poorly excreted into breastmilk and are undetectable by 3 days after an injection. Some authors recommend withholding breastfeeding for this period of time. However, filgrastim has been safely given orally to neonates and is not orally absorbed by neonates, so any filgrastim that is excreted into milk is unlikely to adversely affect the breastfed infant.
Quoted from Filgrastim — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised July 15, 2026.
How much filgrastim gets into breastmilk
Granulocyte colony-stimulating factor (G-CSF) is a normal component of breastmilk. In the United States, the biosynthetic forms that are available for exogenous administration are filgrastim and pegfilgrastim. Other biosynthetic forms of G-CSF are available in other countries. Lenograstim is a glycosylated recombinant G-CSF whereas filgrastim is not glycosylated.
Maternal Levels. A nursing mother who was 4 months postpartum was given the recombinant G-CSF product lenograstim in order to donate peripheral blood stem cells. She was given lenograstim subcutaneously in doses of 300 mcg on day 1,600 mcg daily on days 2 to 4 and 300 mcg daily on days 5 and 6 of therapy. G-CSF concentration in milk was less than 5 ng/L before therapy. G-CSF milk levels increased during therapy with levels of about 58 ng/L on day 4, 78 ng/L on day 5, and 85.7 ng/L on day 6. Sampling times were not stated. The maximum amount in milk represents an infant dosage of about 0.013 mcg/kg which is 13% of an infant subcutaneous dose of exogenous G-CSF and 0.13% of the maternal weight-adjusted dosage.
A woman received subcutaneous injections of filgrastim in the following doses: 600 mcg on day 1,300 mcg twice daily on days 2 to 5, and 300 mcg once on day 6 prior to harvesting white cells for donation. She was nursing her 25-day-old infant and milk G-CSF levels were measured once daily just before the first dose of the day. G-CSF was first detectable (>10 ng/L) in whole milk 12 hours after the start of the regimen, had a peak milk concentration of 188 ng/L at 22 hours after the start of the regimen, and then after 43 hours, slowly declined until G-CSF was undetectable (<10 ng/L) in breastmilk 70 hours after the last dose.
A patient received granulocyte colony stimulating factor (presumably filgrastim) for hematopoietic progenitor cell mobilization prior to transplantation. The exact dosage and regimen were not stated in the published abstract. The peak concentration of G-CSF in donor milk was at 592 ng/L 48 hours after the first dose. G-CSF remained detectable in donor milk for 48 hours after the final dose.
Infant Levels. Published information on absorption of filgrastim from breastmilk was not found as of the revision date. However, a study in which an oral dose of 100 mcg/kg of filgrastim (10 times the subcutaneous dose) was given to preterm infants found that filgrastim was not absorbed.
What has been seen in breastfed infants
Published information on the effects of filgrastim in breastmilk was not found as of the revision date. However, oral filgrastim 20 mcg daily for 5 days has been given to preterm infants with stage I necrotizing enterocolitis (NEC). Filgrastim appeared to halt progression to more severe stages of NEC in this small study.
Effects on milk supply
Relevant published information was not found as of the revision date.
Frequently asked questions
Can you take filgrastim while breastfeeding?
Filgrastim in the pharmaceutical name for granulocyte colony-stimulating factor (G-CSF). The full record is quoted on this page, and the decision is one to make with the person who prescribed it — LactMed itself states it is not a substitute for professional judgement.
Does filgrastim pass into breastmilk?
LactMed's measured drug levels for filgrastim are quoted in full on this page, under "How much gets into breastmilk".
Do I need to pump and dump after taking filgrastim?
LactMed does not frame its records that way — it reports measured drug levels in milk and what has been observed in breastfed infants, which is what this page quotes. "Pump and dump" advice for a specific drug and dose should come from your clinician or a pharmacist, not from a general rule.
More on filgrastim
LactMed states that the information it presents is not a substitute for professional judgement, and that you should consult your healthcare provider for breastfeeding advice related to your particular situation. Nothing on this page is medical advice.