Last update Oct. 13, 2022

Cloxacillin; Cloxacillin Sodium


Safe substance and/or breastfeeding is the best option.

It is a beta-lactam antibiotic, from the penicillin group, resistant to beta-lactamases. Widely used for treatment of Mastitis since it has an effective activity against Staphylococcus aureus. Oral, intramuscular or intravenous administration.

It is excreted in breast milk in clinically insignificant amounts (Matsuda 1984).

Except for occasional and transient gastroenteritis, no harmful effects have been found among breastfed infants from treated mothers. (Ito 1993) 

Although rare, the possibility of transient gastroenteritis due to alteration of the intestinal flora in infants whose mothers take antibiotics should be taken into account. (Benyamini 2005, Ito 1993) 

Several medical societies and expert authors consider the use of this medication to be safe during breastfeeding. (Amir 2014 & 2011, Spencer 2008, Nordeng 2003, Bodley 2000)

List of Essential Medicines by WHO 2002: compatible with breastfeeding. (WHO 2002)


We do not have alternatives for Cloxacillin; Cloxacillin Sodium since it is relatively safe.

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

Cloxacillin; Cloxacillin Sodium is also known as

Cloxacillin; Cloxacillin Sodium in other languages or writings:


Cloxacillin; Cloxacillin Sodium belongs to this group or family:


Main tradenames from several countries containing Cloxacillin; Cloxacillin Sodium in its composition:


Variable Value Unit
Oral Bioavail. 40 - 60 %
Molecular weight 436 daltons
Protein Binding 94 %
VD 0.1 l/Kg
pKa 3.75 -
Tmax 1 - 2 hours
0.5 - 1 hours
Theoretical Dose 0.03 - 0.06 mg/Kg/d
Relative Dose 0.1 - 0.4 %
Ped.Relat.Dose 0.06 - 0.1 %


  1. Amir LH. y el Comité de protocolos de la Academy of Breastfeeding Medicine. Protocolo clínico de la ABM n.o 4: Mastitis, modi cado en marzo de 2014. Breastfeed Med. 2014;9(5):239-243. Abstract Full text (link to original source) Full text (in our servers)
  2. Amir LH; Academy of Breastfeeding Medicine Protocol Committee. ABM Clinical Protocol #4: Mastitis, Revised March 2014. Breastfeed Med. 2014;9(5):239-243. Abstract Full text (link to original source) Full text (in our servers)
  3. Amir LH, Pirotta MV, Raval M. Breastfeeding--evidence based guidelines for the use of medicines. Aust Fam Physician. 2011 Sep;40(9):684-90. Review. Abstract Full text (link to original source) Full text (in our servers)
  4. Spencer JP. Management of mastitis in breastfeeding women. Am Fam Physician. 2008 Abstract Full text (link to original source) Full text (in our servers)
  5. Benyamini L, Merlob P, Stahl B, Braunstein R, Bortnik O, Bulkowstein M, Zimmerman D, Berkovitch M. The safety of amoxicillin/clavulanic acid and cefuroxime during lactation. Ther Drug Monit. 2005 Abstract
  6. Nordeng H, Tufte E, Nylander G. [Treatment of mastitis in general practice]. Tidsskr Nor Laegeforen. 2003 Abstract
  7. WHO / UNICEF. BREASTFEEDING AND MATERNAL MEDICATION Recommendations for Drugs in the Eleventh WHO Model List of Essential Drugs. Department of Child and Adolescent Health and Development (WHO/UNICEF) 2002 Abstract Full text (link to original source) Full text (in our servers)
  8. Bodley V, Powers D. Case management of a breastfeeding mother with persistent oversupply and recurrent breast infections. J Hum Lact. 2000 Abstract
  9. Ito S, Blajchman A, Stephenson M, Eliopoulos C, Koren G. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993 May;168(5):1393-9. Abstract
  10. Matsuda S. Transfer of antibiotics into maternal milk. Biol Res Pregnancy Perinatol. 1984;5(2):57-60. Abstract

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