Is Lysine safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Lysine. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
Relevant published information was not found as of the revision date.
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
The dietary reference intake (DRI) for infants up to 6 months of age is 640 mg or 107 mg/kg daily of lysine.[ 1 ] Maternal Levels . The total lysine content of milk averages 915 mg/L in the first month postpartum and decreases to an average of 622 mg/L in month 6 postpartum.[ 3 ] Mature milk is considered to contain an average of about 755 mg/L of lysine.[ 4 ] No information is available on levels after the use of lysine supplements. Infant Levels . Relevant published information was not found as of the revision date.
Alternatives LactMed lists
“No published information” means the studies do not exist yet — not that Lysine is known to be harmful, and not that it is known to be safe. Your prescriber or pharmacist can weigh your baby's age and whether a better-studied alternative would do the same job. Worth asking before stopping a medicine you need.
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.