Last update: July 21, 2017


Very Low Risk for breastfeeding

Safe. Compatible.
Minimal risk for breastfeeding and infant.

Mixture of 5 parts of Sulfamethoxazole and 1 part of Trimethoprim. See info on items separately.

Trimethoprim is excreted into breast milk at 4 to 10% of corrected pediatric dose.

No adverse effects have been shown in breastfed infants. Used for treatment of infants older than one month.

Sulfamethoxazole is excreted in low levels into breast milk.No adverse effects have been shown in breastfed infants. Cautious use for treatment of premature infants with hyperbilirubinemia or G-6-P-D deficiency is required. Avoid use in affected patients .

Check-up for infant jaundice.

Be aware of false negative results of bacterial cultures when the mother is on antibiotics and diarrheal disease due to intestinal flora imbalance.

The American Academy of Pediatrics rates it compatible with breastfeeding.

Eleventh WHO Model List of Essential Drugs 2002: Compatible with breastfeeding for older, healthy full- term infants.

See below the information of these related products:


Suggestions made at e-lactancia are done by APILAM´s pediatricians and pharmacists, and are based on updated scientific publications.
It is not intended to replace the relationship you have with your doctor but to compound it.

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

TMP-SMX is also known as Sulfamethoxazole & Trimethoprim. Here it is a list of alternative known names::


TMP-SMX belongs to this group or family:


Main tradenames from several countries containing TMP-SMX in its composition:

  • Abactrim™. Contains other elements than TMP-SMX in its composition
  • Bactrim™. Contains other elements than TMP-SMX in its composition
  • Cotrim™. Contains other elements than TMP-SMX in its composition
  • Septrim™. Contains other elements than TMP-SMX in its composition


Variable Value Unit
Oral Bioavail. 100 %
Molecular weight S/T: 253 / 290 daltons
Protein Binding S/T: 63 / 45 %
Tmax 1 - 4 hours
T1/2 6 - 12 hours
M/P ratio S/T: 0,06 / 1,3 -
Theoretical Dose S/T: 0,8 / 0,3-0,8 mg/Kg/d
Relative Dose S/T: 1-5 / 6-15 %
Relat.Ped.Dose S/T: 3 / 4-10 %


  1. Amir LH. ABM Clinical Protocol #4: Mastitis, Revised March 2014. Breastfeed Med. 2014 Abstract Full text (link to original source) Full text (in our servers)
  2. Butler DC, Heller MM, Murase JE. Safety of dermatologic medications in pregnancy and lactation: Part II. Lactation. J Am Acad Dermatol. 2014 Mar;70(3):417.e1-10; quiz 427. Abstract
  3. Amir LH, Pirotta MV, Raval M. Breastfeeding--evidence based guidelines for the use of medicines. Aust Fam Physician. 2011 Abstract Full text (link to original source) Full text (in our servers)
  4. Chen LH, Zeind C, Mackell S, LaPointe T, Mutsch M, Wilson ME. Breastfeeding travelers: precautions and recommendations. J Travel Med. 2010 Jan-Feb;17(1):32-47. Abstract Full text (link to original source) Full text (in our servers)
  5. Mitrano JA, Spooner LM, Belliveau P. Excretion of antimicrobials used to treat methicillin-resistant Staphylococcus aureus infections during lactation: safety in breastfeeding infants. Pharmacotherapy. 2009 Sep;29(9):1103-9. Abstract
  6. Spencer JP. Management of mastitis in breastfeeding women. Am Fam Physician. 2008 Abstract Full text (link to original source) Full text (in our servers)
  7. Kaiser J, McPherson V, Kaufman L, Huber T. Clinical inquiries. Which UTI therapies are safe and effective during breastfeeding? J Fam Pract. 2007 Abstract
  8. Forna F, McConnell M, Kitabire FN, Homsy J, Brooks JT, Mermin J, Weidle PJ. Systematic review of the safety of trimethoprim-sulfamethoxazole for prophylaxis in HIV-infected pregnant women: implications for resource-limited settings. AIDS Rev. 2006 Abstract
  9. Mahadevan U, Kane S. American gastroenterological association institute technical review on the use of gastrointestinal medications in pregnancy. Gastroenterology. 2006 Jul;131(1):283-311. Review. Abstract Full text (link to original source) Full text (in our servers)
  10. 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 Full text (link to original source) Full text (in our servers)
  11. 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)
  12. Chin KG, McPherson CE 3rd, Hoffman M, Kuchta A, Mactal-Haaf C. Use of anti-infective agents during lactation: Part 2--Aminoglycosides, macrolides, quinolones, sulfonamides, trimethoprim, tetracyclines, chloramphenicol, clindamycin, and metronidazole. J Hum Lact. 2001 Feb;17(1):54-65. Abstract
  13. 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
  14. 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
  15. Borderon E, Soutoul JH et al. [Excretion of antibiotics in human milk]. Med Mal Infect. 1975;5:373-6. 1975
  16. Miller RD, Salter AJ. \ The passage of trimethoprim/sulpha-methoxazole into breast milk and its significance. \ Proceedings of the 8th International Congress of Chemotherapy, Athens. Hellenic Soc Chemother. 1974;1:687. 1974
  17. Arnauld R, Soutoul JH, Gallier J et al. Etude du passage de la trimethprim dans le lait maternel. \ [Study on the passage of trimethoprin into mother's milk]. Ouest Med. 1972;25:959-64.4. 1972
  18. Rasmussen F. \ Mammary excretion of sulphonamides. Acta Pharmacol Toxicol 1958; 15: 139-48. 1958

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