May 27 2022


Risks to the infant

There are no direct communications regarding the health risks of infants whose mothers received azithromycin while breastfeeding. Other antibiotics of the same group, such as erythromycin, are well documented relative to production of hypertrophic pyloric stenosis in the infant, iincreasing the risk of suffering this process eight to ten times more compared to children not exposed[1][2][3][4][5][6].

A cohort study in Denmark, covering a period of 10 years (1991-2000) that included data from nearly 43,000 term pregnancies in which 1166 nursing mothers received a macrolide (erythromycin = 1012; azithromycin = 101; clarithromycin = 24; roxithromycin= 268 and spiramycin = 3), showed an increased risk to suffer hypertrophic stenosis of the pylorus, although not were included disaggregated data for azithromycin and statistical accuracy was poor[7]. Data analysis of prenatal macrolide intake also shows an increased risk of postnatal pyloric stenosis[8].

Some authors call for caution about the possibility of the same adverse effects on the pylorus that with erythromycin[9].

Influence on lactation

Very little is known about the pharmacokinetics of azithromycin in human milk and its transfer to the infant. A case referred in a nursing mother who received three consecutive doses, with 24 hours between them (1000 mg, 500 mg and 500 mg), reached its maximum concentration after the last dose (2.8 ng/ml)[10]. It is estimated that the total amount received by the baby is 0.4 mg/kg, far away from the standard 10 mg/kg as a loading dose for that age.


Azithromycin is considered compatible with breastfeeding, although it is noted the absence of data supporting its safety or risk.


1. Very early exposure to erythromycin and infantile hypertrophic pyloric stenosis. Cooper WO, Griffin MR, Arbogast P, Hickson GB, Gautam S, Ray WA.Arch Pediatr Adolesc Med. 2002 Jul;156(7):647-50.
2. Honein MA, Paulozzi LJ, Himelright IM, Lee B, Cragan JD, Patterson L, Correa A, Hall S, Erickson JD. Infantile hypertrophic pyloric stenosis after pertussis prophylaxis with erythromcyin: a case review and cohort study. Lancet. 1999 Dec 18-25;354(9196):2101-5.
3. Mahon BE, Rosenman MB, Kleiman MB. Maternal and infant use of erythromycin and other macrolide antibiotics as risk factors for infantile hypertrophic pyloric stenosis. J Pediatr. 2001 Sep;139(3):380-4.
4. Hypertrophic pyloric stenosis in infants following pertussis prophylaxis with erythromycin--Knoxville, Tennessee, 1999. MMWR Morb Mortal Wkly Rep. 1999 Dec 17;48(49):1117-20.
5. SanFilippo A. Infantile hypertrophic pyloric stenosis related to ingestion of erythromycine estolate: A report of five cases. J Pediatr Surg. 1976 Apr;11(2):177-80.
6. Erythromycin-induced pyloric stenosis in infants. Prescrire Int. 2001 Feb;10(51):16.
7. Sorensen HT, Skriver MV, Pedersen L, Larsen H, Ebbesen F, Schonheyder HC. Risk of infantile hypertrophic pyloric stenosis after maternal postnatal use of macrolides. Scand J Infect Dis. 2003; 35(2):104-6.
8. Cooper WO, Ray WA, Griffin MR. Prenatal prescription of macrolide antibiotics and infantile hypertrophic pyloric stenosis.Obstet Gynecol. 2002 Jul; 100(1):101-6.
9. Hauben M, Amsden GW. The association of erythromycin and infantile hypertrophic pyloric stenosis: causal or coincidental? Drug Saf. 2002;25(13):929-42.
10. Kelsey JJ, Moser LR, Jennings JC, Munger MA.Presence of azithromycin breast milk concentrations: a case report. Am J Obstet Gynecol. 1994 May;170(5 Pt 1):1375-6.

Warning of the manufacturer:

There are no data regarding the transfer of azithromycin to the milk secretion. Since many drugs are secreted in breast milk, azithromycin should not be used in treating nursing women unless the physician considers the potential benefits justify the possible risks to the child.