Last update Oct. 14, 2022

Nafcillin Sodium

Very Low Risk

Safe. Compatible. Minimal risk for breastfeeding and infant.

It is a penicillinase-resistant penicillin that is used in a similar way to flucloxacillin in the treatment of benzylpenicillin-resistant staphylococcal infections. Intravenous or intramuscular administration.

Since the last update we have not found published data on its excretion in breastmilk.

Its high percentage of protein binding make it highly unlikely that significant quantities will pass into breast milk.

Because it lacks of oral bioavailability, seems difficult any pass to the infant’s plasma through the breast milk ingested, except on premature infants and immediate neonatal period, in which there may be an increased intestinal permeability.

Expert authors consider the use of this medication to be safe during breastfeeding. (Hale, LacMed, Briggs 2015)


Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Nafcillin Sodium in other languages or writings:


Nafcillin Sodium belongs to this group or family:


Main tradenames from several countries containing Nafcillin Sodium in its composition:


Variable Value Unit
Oral Bioavail. 50 %
Molecular weight 455 daltons
Protein Binding 89.9 ± 1.5 %
Tmax 0.5 - 1 hours
0.5 - 1.5 hours


  1. LactMed. Drugs and Lactation Database (LactMed). Internet. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: 2006 - Consulted on April 16, 2024 Full text (link to original source)
  2. Hale TW. Medications & Mothers' Milk. 1991- . Springer Publishing Company. Available from Consulted on April 10, 2024 Full text (link to original source)
  3. Briggs GG, Freeman RK, Towers CV, Forinash AB. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. Wolters Kluwer Health. Tenth edition (acces on line) 2015

Total visits


Help us improve this entry

How to cite this entry

Do you need more information or did not found what you were looking for?

   Write us at

e-lactancia is a resource recommended by Academy of Breastfeeding Medicine - 2012 of United States of America

Would you like to recommend the use of e-lactancia? Write to us at corporate mail of APILAM