Last update Jan. 29, 2022



Safe substance and/or breastfeeding is the best option.

It is a short-acting sulfonamide that has been used similarly to sulfamethoxazole. Oral administration every 4 to 6 hours.

It is excreted in breast milk in clinically insignificant amounts and urinary levels in infants whose mothers were taking it were very low. (Kaufmann 1980)

Caution with those neonates suffering of hyperbilirrubinemia or Glucose-6-phosphate dehydrogenase (G6PD) deficiency is required. (AAP 2001)

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

Expert authors consider the use of this madication to be compatible during breastfeeding. (Hale, LactMed, Briggs 2015)

American Academy of Pediatrics: Maternal Medication Usually Compatible With Breastfeeding. (AAP 2001)

Due to the greater toxicity than other antimicrobials and their high acquired resistance, the use of sulfonamides is currently very scarce (Pérez 2003).


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

Sulfisoxazole is also known as

Sulfisoxazole in other languages or writings:


Main tradenames from several countries containing Sulfisoxazole in its composition:


Variable Value Unit
Oral Bioavail. 100 %
Molecular weight 267 daltons
Protein Binding 91 %
Tmax 4 hours
7.8 hours
M/P ratio 0.06 - 0.22 -
Relative Dose 0.3 %


  1. Pérez-Trallero E, Iglesias L. Tetraciclinas, sulfamidas y metronidazol. [Tetracyclines, sulfonamides and metronidazole]. Enferm Infecc Microbiol Clin. 2003 Nov;21(9):520-8; quiz 529, 533. Review. Spanish. Abstract Full text (link to original source)
  2. AAP - American Academy of Pediatrics Committee on Drugs. Transfer of drugs and other chemicals into human milk. Pediatrics. 2001 Sep;108(3):776-89. Abstract Full text (link to original source) Full text (in our servers)
  3. 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
  4. Fulton B, Moore LL. Antiinfectives in breastmilk. Part II: Sulfonamides, tetracyclines, macrolides, aminoglycosides and antimalarials. J Hum Lact. 1992 Dec;8(4):221-3. Review. No abstract available. Abstract
  5. Kauffman RE, O'Brien C, Gilford P. Sulfisoxazole secretion into human milk. J Pediatr. 1980 Nov;97(5):839-41. No abstract available. Abstract

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