Drug Levels and Effects:

Summary of Use during Lactation:

Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy. Limited information indicates that a maternal dose of methotrexate up to 65 mg (or 50 mg/square meter) produces low levels in milk, leading some authors to state that low single or weekly doses, such as those used for rheumatoid arthritis, are of low risk to the breastfed infant.[1][2][3][4] If methotrexate use is undertaken, monitoring of the infant's complete blood count and differential is advisable.

Drug Levels:

Maternal Levels.

One patient who was 1 month postpartum given 22.5 mg (15 mg/square meter) methotrexate daily by mouth for choriocarcinoma. Milk was collected at various times of the first 12 days of therapy. A peak milk level of 2.3mcg/L occurred 10 hours after the first dose. However, the milk level was relatively constant during the period from 4 to 10 hours after the dose, after which it began to drop. Peak milk levels on the second and third days of administration were 2.7 mcg/L. The authors estimated that a cumulative amount of 0.32 mcg would be excreted in milk during the first 12 hours after this dose.[1]

A woman was given a single intramuscular dose of 65 mg (50 mg/square meter) of methotrexate for ectopic pregnancy. Six milk samples were obtained from 1 to 24 hours after the dose. Methotrexate was undetectable (assay limit not stated) in all milk samples.[4]

Infant Levels.

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

Effects in Breastfed Infants:

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

Possible Effects on Lactation:

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

Alternate Drugs to Consider:

(Rheumatoid Arthritis) Auranofin,Etanercept,Gold Sodium Thiomalate,Hydroxychloroquine,Infliximab,Penicillamine,Sulfasalazine


1. Johns DG, Rutherford LD et al. Secretion of methotrexate in human milk. Am J Obstet Gynecol. 1972;112:978-80. PMID:5042796
2. Moretti ME, Lee A, Ito S. Which drugs are contraindicated during breastfeeding? Can Fam Physician. 2000;46:1753-7. PMID:11013791
3. Ostensen M. Management of early aggressive rheumatoid arthritis during pregnancy and lactation. Expert Opin Pharmacother. 2009;10:1469-79. PMID:19505214
4. Tanaka T, Walsh W, Verjee Z et al. Methotrexate use in a lactating woman with an ectopic pregnancy. Birth Defects Res A Clin Mol Teratol. 2009;85:494. Abstract.

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Abortifacient Agents, Nonsteroidal

  • Antimetabolites, Antineoplastic

  • Antirheumatic Agents

  • FolicAcid
  • Antagonists

  • Immunosuppressive Agents

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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