Medications for Lactating Mothers in the Emergency Department

By Liz Rozycki, PharmD, Specialty Practice Pharmacist, Emergency Medicine, OSU

There is no shortage of information regarding the benefits of breast milk for infants and mothers, likewise, there is no shortage of challenges that face a mother who is trying to breastfeed her baby through the recommended one to two years of age. Medication use during lactation, for acute or chronic conditions, poses a challenge to mothers and clinicians.  Is this medication safe for my baby? Is there an alternative? Do I have to “pump and dump”?  Especially for mothers who are presenting to the emergency department, if a medication is required, there is likely some reason they came in and treatment is warranted.

The easy, conservative and often unwarranted approach to medication use in lactating mothers is instructing them to pump and dump during medication use. Depending on the duration of medication therapy, this recommendation may result in a mother deferring her medical care in lieu of her child or may be the end of the breastfeeding journey. Although some mothers may have a stash of milk accumulated and may be able to pump and dump for a short period of time, this may not always be the case.  The goal of this blog post is to make sure all other options have been evaluated before you discharge a patient with the recommendation to “pump and dump”. 

Most drugs transfer into breast milk via passive diffusion but the concentration is relatively low and may not have any adverse effects on the infant. When evaluating the likelihood of medication transfer to breast milk, some basic pharmacokinetic properties can be reviewed (Table 1).  The most important predictor of drug transfer to breast milk is maternal plasma concentration, as the level rises in maternal plasma, drug diffuses into breast milk and when the level decreases in maternal plasma, drug diffuses back into plasma.  For some medications, scheduling medication administration apart from feedings may help to limit infant exposure.  In addition, clinicians should evaluate the infant for risk of medication side effects.  Age and clinical stability should be evaluated as premature and newborn infants may be at higher risk for medication side effects.

Table 1: Drug properties and infant factors influencing exposure to medication from breast milk

Drug properties influencing medication concentration in breast milk Infant factors influencing medication exposure
–          Maternal plasma concentration

–          Low protein binding

–          Low molecular weight

–          High lipid solubility

–          High pKa, weakly basic drugs

–          Oral bioavailability to infant


–          Age, premature and newborn infants may be at higher risk for medication side effects

–          Frequency and amount of feedings

–          Renal and hepatic function


When determining medication therapy for lactating mothers, first, determine if your standard or first-line therapy to treat a condition is considered safe with breastfeeding. This can be accomplished by utilizing drug information resources, such as LactMed® ( or consulting your clinical pharmacist.  Second, if the standard therapy is not safe or the data is unclear, consider alternatives that may be safe – think out of the box if needed, alternative drug classes, routes of administration, timing medication administration apart from feedings, etc.  Drug information resources, such as LactMed®, often provide alternative medications options to aid in your evaluation.  Finally, if no appropriate alternative can be found, counsel the patient on risks and benefits of treatment and provide an appropriate education on how long the drug may be in the system and possibly transferred in breast milk.

The next time you care for a lactating mother, be sure to take a few extra seconds to evaluation medication therapies for safety (or call your clinical pharmacist) and ensure the best care for both the mother and her infant!


1. Hale TW, Rowe HE. Medications and Mother’s Milk. 16th ed. Plano, TX: Hale Publishing; 2014.