Medications and Breastfeeding: Tips for Giving Accurate Information to Mothers

​Medications and Breastfeeding: Tips for Giving Accurate Information to Mothers

By Jennifer Thomas, MD, FAAP, Chapter Breastfeeding Coordinator Steering Committee Vice Chief, Wisconsin Chapter Breastfeeding Coordinator

Advising a breastfeeding mother on the compatibility of her medications and breastfeeding can often be a source of confusion. Clinicians must consider several factors: the benefit the medication will give to the mother; the risk of discontinuation of breastfeeding, even temporarily, to the baby; the risk of the medication to the baby and the risk of the medication to the maternal milk supply. Unfortunately, the typical sources of information on medications and breastmilk, such as Epocrates, Clin-eguide, Lexi-Comp and the PDR, are often inaccurate
and may lead to unnecessary interruption or weaning from breastfeeding.

The most accurate sources of information to aid clinicians about medications in breastfeeding mothers are the National Library of Medicine’s LactMed, ( a searchable database of drugs and other chemicals to which breastfeeding mothers may be exposed and Dr. Thomas Hale’s ”Medications and Mother’s Milk” and his website forums at 

LactMed is peer-reviewed, fully referenced, continually updated and a free service. The data given for each drug includes maternal and infant levels of drugs, possible effects on breastfed infants and on lactation, and alternate drugs to consider.

Clinical points to remember about choosing medications in breastfeeding mothers:

  • Breastfeeding is important and even temporary disruption can affect milk supply. Information on medications and breastfeeding is easily available online through LactMed’s searchable database. Advice to pump and discard milk assumes that the mother can afford or has a breast pump, that she knows how to use that pump, and that her baby will know how to take a bottle.
    Infant formula may not be an acceptable substitute, even for short periods of time.

  • A drug must reach the maternal serum in order to penetrate into milk. Use topical therapy when possible since serum levels are usually very small.

  • Transfer of medication from the maternal serum into milk depends on the drug’s oral availability, lipid solubility, molecular weight, protein binding and half life. Try to choose drugs with low oral absorption, low lipid solubility, large molecular weight, high protein binding and a short half life.

  • Medications that we use for a newborn baby are generally safe to use in a nursing mom.

  • Pregnancy risk is not the same as breastfeeding risk.

  • Radiologic agents, such as x-ray, and contrast agents for MRI and CT have little to no oral availability and therefore do not require cessation of breastfeeding.

  • The gestational age of the baby should be taken into consideration. Medications in preterm infants may be different than that in term infants. The chronological age of the baby is also important. For example, the amount of medication transferred to an eleven month old may be
    much different than that transferred to a two month old simply because of the amount of breast milk each age group would be consuming.

  • No medication is safe. “Compatible” is a better word since it acknowledges a risk-benefit balance. . . “Erring on the side of caution” would mean preserving the breastfeeding relationship since very few medications are truly incompatible with breastfeeding.