Last update July 31, 2018

Nalidixic Acid

Low Risk

Possibly safe. Probably compatible. Mild risk possible. Follow up recommended. Read the Comment.

An antibacterial quinolone used in the treatment of urinary tract infections.
Oral administration 4 times a day.
Its use is authorized in infants from 3 months of age (Sanofi 2008).

It is excreted in breastmilk in clinically insignificant amounts (Traeger 1980), much lower than the dose used in infants.

Hemolysis has been observed in a newborn whose breastfeeding mother was taking nalidixic acid (Chin 2001 --> Belton 1965).

Until there is more published data on this drug in relation to breastfeeding, safer known alternatives may be preferable, especially during the neonatal period and in case of prematurity or glucose-6-phosphate dehydrogenase deficiency (WHO 2002).

The possible negativity of cultures in febrile infants whose mothers take antibiotics should be taken into account, as well as the possibility of gastroenteritis due to alteration of the intestinal flora (Ito 1993).

American Academy of Pediatrics: medication usually compatible with breastfeeding (AAP 2001).


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

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Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Nalidixic Acid in other languages or writings:


Nalidixic Acid belongs to this group or family:


Main tradenames from several countries containing Nalidixic Acid in its composition:


Variable Value Unit
Oral Bioavail. 96 %
Molecular weight 232 daltons
Protein Binding 93 %
VD 0.5 l/Kg
pKa 5.95 -
Tmax 1 - 2 hours
1.1 - 7 hours
M/P ratio 0.08 - 0.13 -
Theoretical Dose 0.175 mg/Kg/d
Relative Dose 0.5 %
Ped.Relat.Dose 0.3 %


  1. Sanofi. Nalidixic acid. Drug Summary. 2008 Full text (in our servers)
  2. 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)
  3. 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
  4. 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)
  5. 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
  6. Traeger A, Peiker G. Excretion of nalidixic acid via mother's milk. Arch Toxicol Suppl. 1980 Abstract
  7. Belton EM, Jones RV. Haemolytic anaemia due to nalidixic acid. Lancet. 1965 Abstract

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