Azithromycin use while Breastfeeding
Drugs containing Azithromycin: Zithromax, Azithromycin Dose Pack, Z-Pak, Azasite, Zmax
Azithromycin Levels and Effects while Breastfeeding
Summary of Use during Lactation
Because of the low levels of azithromycin in breastmilk and use in infants in higher doses, it would not be expected to cause adverse effects in breastfed infants. Monitor the infant for possible effects on the gastrointestinal flora, such as diarrhea, candidiasis (thrush, diaper rash). Unconfirmed epidemiologic evidence indicates that the risk of hypertrophic pyloric stenosis in infants might be increased by maternal use of macrolide antibiotics during breastfeeding.
Maternal Levels. A woman who was 1 day postpartum was given 1 g of azithromycin orally. Forty-eight hours later her milk azithromycin was 0.64 mg/L. An oral regimen of 500 mg daily for 5 days was started and more milk samples were obtained. One hour after the first dose, breastmilk contained 1.3 mg/L and 30 hours after the third dose milk contained 2.8 mg/L. Because of the slow clearance and accumulation of azithromycin, it is difficult to interpret these milk levels. The dose that the infant would receive in milk would gradually increase for several days because maternal blood levels would increase until steady-state had been reached. If the level of 2.8 mg/L is used as an approximate trough level, an exclusively breastfed infant would receive a minimum of 0.42 mg/kg daily compared to the dose of 5 to 10 mg/kg daily used in infants of 6 months and over.
In a study of 30 women given azithromycin 500 mg intravenously 15, 30 or 60 minutes prior to incision for cesarean section, 8 women subsequently breastfed their infants. Multiple breastmilk samples were collected during the first 8 hours postpartum and then once again between 12 and 48 hours postpartum. Azithromycin persisted in breastmilk up to 48 hours after a dose with a median breastmilk concentration of 1713 mcg/L at a median of 30.7 hours after the dose, and a breastmilk half-life of about 24 hours. The authors stated that the overall exposure of the infant was minimal and not likely to be clinically important.
Infant Levels. Relevant published information was not found as of the revision date.
Effects in Breastfed Infants
A cohort study of infants diagnosed with infantile hypertrophic pyloric stenosis found that affected infants were 2.3 to 3 times more likely to have a mother taking a macrolide antibiotic during the 90 days after delivery. Stratification of the infants found the odds ratio to be 10 for female infants and 2 for male infants. All of the mothers of affected infants nursed their infants. Most of the macrolide prescriptions were for erythromycin, but only 7% were for azithromycin. However, the authors did not state which macrolide was taken by the mothers of the affected infants.
A study comparing the breastfed infants of mothers taking amoxicillin to those taking a macrolide antibiotic found no instances of pyloric stenosis. However, most of the infants exposed to a macrolide in breastmilk were exposed to roxithromycin. Only 10 of the 55 infants exposed to a macrolide were exposed to azithromycin. Adverse reactions occurred in 12.7% of the infants exposed to macrolides which was similar to the rate in amoxicillin-exposed infants. Reactions included rash, diarrhea, loss of appetite, and somnolence.
Eight women who were given azithromycin 500 mg intravenously 15, 30 or 60 minutes prior to incision for cesarean section breastfed their newborn infants. No adverse events were noted in their infants.
Possible Effects on Lactation
Relevant published information was not found as of the revision date.
Alternate Drugs to Consider
1. Kelsey JJ, Moser LR, Jennings JC et al Presence of azithromycin breast milk concentrations: a case report. Am J Obstet Gynecol. 1994;170:1375-6. PMID: 8178871
2. Sutton A, Acosta E, Larson K et al. Azithromycin accumulates in breast milk following a single dose for cesarean prophylaxis. Am J Obstet Gynecol. 2014;210 (1 Suppl):S235. Abstract.
3. Sorensen HT, Skriver MV, Pedersen L et al. Risk of infantile hypertrophic pyloric stenosis after maternal postnatal use of macrolides. Scand J Infect Dis. 2003;35:104-6. PMID: 12693559
4. Goldstein LH, Berlin M, Tsur L et al. The safety of macrolides during lactation. Breastfeed Med. 2009;4:197-200. PMID: 19366316
CAS Registry Number
- Anti-Bacterial Agents
- Anti-Infective Agents
LactMed Record Number
Information from the National Library of Medicine's LactMed Database.
Last Revision Date
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