Can you take vincristine 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.
Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy. It is probably impractical to resume breastfeeding after vincristine therapy because of the drug's long half-life. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.
Quoted from Vincristine — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised August 15, 2024.
How much vincristine gets into breastmilk
Maternal Levels. A woman was diagnosed with B-cell non-Hodgkins lymphoma at 4 months postpartum. She received R-CHOP therapy every 21 days for 6 cycles. It consisted of rituximab 375 mg/sq. m, cyclophosphamide 750 mg/sq. m, doxorubicin 50 mg/sq. m, vincristine 1.4 mg/sq. m (capped at 2 mg) plus prednisone 40 mg/sq. m daily. She also received oral 300 mg of allopurinol daily during the whole therapy course. Milk samples were collected twice daily during the first 3 cycles then once daily for the remaining cycles for a total of 290 samples. Vincristine was not detectable in any samples. However, the assay method was relatively insensitive, so low levels of the drug might be present in breastmilk.
Infant Levels. Relevant published information was not found as of the revision date.
What has been seen in breastfed infants
In a 4-month-old, neutropenia was probably caused by cyclophosphamide in a mother 9 days after the last of 6 weekly doses of 800 mg cyclophosphamide intravenously, 2 mg vincristine intravenously and daily doses of 30 mg of prednisolone orally. Neutropenia persisted at least 12 days and was accompanied by a brief episode of diarrhea. The contribution of vincristine to the neutropenia cannot be determined.
A woman was diagnosed with B-cell lymphoma at 27 weeks of pregnancy. Labor was induced at 34 4/7 weeks and treatment was begun with a standard regimen of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone in unspecified doses on a 21-day cycle, starting on day 2 postpartum. She pumped and discarded her milk and fed her infant donor milk for the first 10 days of each cycle and then breastfed her infant for the remaining 10 days before the next treatment cycle. The 10-day period of breastfeeding abstinence was determined by using about 3 half-lives of vincristine. After completion of 4 cycles of chemotherapy, her infant was reportedly healthy and developing without any complications.
Effects on milk supply
Relevant published information was not found as of the revision date.
Frequently asked questions
Can you take vincristine while breastfeeding?
Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy. 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 vincristine pass into breastmilk?
LactMed's measured drug levels for vincristine are quoted in full on this page, under "How much gets into breastmilk".
Do I need to pump and dump after taking vincristine?
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 vincristine
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.