Last update Jan. 28, 2022

Trimethoprim (TMP)


Safe substance and/or breastfeeding is the best option.

Antibacterial used alone or in combination with sulfonamides. Oral administration in two daily doses.

It is excreted in breast milk in clinically non-significant amount. (Borderon 1975, Miller 1974 y 1973, Arnauld 1972)

No problems have been observed in infants whose mothers were treated. (Ito 1993)

Medication which is used in infants from the second month of age.

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, Briggs 2015, Schaefer2015, Mitrano 2009, Kaiser 2007, Chin 2001)

The American Academy of Pediatric states that it is usually compatible with breastfeeding medication. (AAP 2001)

WHO List of Essential Medicines from 2002 has classified it as compatible with breastfeeding. (OMS-UNICEF 2002)

See below the information of this related product:


We do not have alternatives for Trimethoprim (TMP) 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

Trimethoprim (TMP) is also known as

Trimethoprim (TMP) in other languages or writings:


Trimethoprim (TMP) belongs to this group or family:


Main tradenames from several countries containing Trimethoprim (TMP) in its composition:


Variable Value Unit
Oral Bioavail. 100 %
Molecular weight 290 daltons
Protein Binding 45 %
VD 7.4 l/Kg
pKa 17.3 -
Tmax 1 - 4 hours
8 - 10 hours
M/P ratio 1.3 -
Theoretical Dose 0.3 - 0.8 mg/Kg/d
Relative Dose 6 - 10 %
Ped.Relat.Dose 4 - 10 %


  1. Hale TW. Medications & Mothers' Milk. 1991- . Springer Publishing Company. Available from Consulted on April 10, 2024 Full text (link to original source)
  2. Schaefer C, Peters P, Miller RK. Drugs During Pregnancy and Lactation. Treatment options and risk assessment. Elsevier, Third Edition. 2015
  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
  4. 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
  5. Kaiser J, McPherson V, Kaufman L, Huber T. Clinical inquiries. Which UTI therapies are safe and effective during breastfeeding? J Fam Pract. 2007 Abstract Full text (link to original source)
  6. 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
  7. 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)
  8. 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
  9. 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
  10. Borderon E, Soutoul JH, Borderon JC. Excrétion des antibiotiques dans le lait humain. [Excretion of antibiotics in human milk]. Med Mal Infect. 1975;5:373-6.
  11. Miller RD, Salter AJ. \ The passage of trimethoprim/sulpha-methoxazole into breast milk and its significance. \ Proceedings of the Eighth International Congress of Chemotherapy, Athens. Hellenic Society for Chemotherapy, 1974:687-91. (cit. Briggs 2015) 1974
  12. Miller RD, Salter AJ. The passage of trimethoprim/sul­ famethoxazole into breast milk and its significance. In Daikos GK(ed): Proceedings of the 8th Congress of Chemotherapy, Athens, 1973, Hellenic Society, Athens,1973, p 687-691. (cit. Hale) 1973
  13. Arnauld R, Soutoul JH, Gallier J, Borderon JC, Borderon E. Etude du passage de la trimethprim dans le lait maternel. [A study of the passage of trimethoprim into the maternal milk]. [Study on the passage of trimethoprin into mother's milk]. Ouest Med. 1972;25:959-64. (Cit. Briggs 2015). 1972

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 El Parto Es Nuestro of Spain

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