In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to erythromycin may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care professional.

What is erythromycin?

Erythromycin is an antibiotic. Some brand names include Eryc®, Emgel®, Erygel®, E-mycin® and Ery-Tab®. It can be taken by mouth to treat infections, particularly those of the skin, upper respiratory tract and pelvis. It can also be used in topical forms for treatment of skin conditions and as an ointment for eye infections.

I just found out that I am pregnant. Should I stop taking my erythromycin?

It is not recommended to stop this medication before talking with your healthcare provider. It is important to discuss the benefits of treating your medical condition versus stopping the medication.

Can taking erythromycin in the first trimester cause a miscarriage?

There are no studies looking specifically to see if exposure to erythromycin taken in the first trimester would increase the chance of having a miscarriage. However, studies that have looked at the risk for birth defects have not found a higher rate of miscarriage.

Can taking erythromycin in the first trimester cause a birth defect?

Not likely. A couple of studies have suggested that exposure to erythromycin in the first trimester might be associated with a small increased chance for heart defects. This association has not been confirmed. In fact, the majority of studies have not found an increased chance for birth defects above the background risk when erythromycin is taken in pregnancy.

Can erythromycin cause other pregnancy complications?

Some reports suggest that exposure to erythromycin during pregnancy might be associated with an increased chance of pyloric stenosis (a narrowing of the opening from the stomach to the small intestines). Other studies have not supported this finding. In addition, the majority of studies have not shown an increased chance for adverse outcomes when erythromycin in used later in pregnancy.

Will taking erythromycin during pregnancy affect my baby’s behavior or cause learning problems?

One study that followed children up to age 11 years, did not find that they needed special assistance in school if they were exposed to erythromycin during pregnancy.

Can I take erythromycin when I am breastfeeding?

Yes, erythromycin can be taken by a woman that is breastfeeding. Small amounts of erythromycin can get into breast milk, but it is unlikely to affect the nursing infant. In one study, a higher chance of pyloric stenosis was seen in infants whose breastfeeding mothers were prescribed erythromycin at the time of birth or within ninety days after. While we know the mothers were prescribed the medication we do not know if it was actually taken. A more controlled study did not support an association between exposure to erythromycin while breastfeeding and a higher chance for pyloric stenosis.

Short-term use of erythromycin is generally considered to be compatible with breastfeeding. As with exposure to any antibiotic, the breastfed infant should be closely observed for adverse effects such as diarrhea, diaper rash, or thrush (yeast infection in mouth). Contact the baby’s healthcare provider if you notice any symptoms. Be sure to talk with your healthcare provider about all of your breastfeeding questions.

What if the father of the baby takes erythromycin?

There are no studies looking at possible risks to a pregnancy when the father takes erythromycin. In general, medications that the father takes do not increase the risk to a pregnancy. For more information, please see the MotherToBaby fact sheet on Paternal Exposures at:

Selected References:

  • Bahat Dinur A, et al. 2013. Fetal safety of macrolides. Antimicrob Agents Chemother 57(7):3307-11.
  • Berard A, et al. 2015. Use of macrolides during pregnancy and the risk of birth defects: a population-based study. Pharmacoepidemiol Drug Saf 24(12): 1241-1248.
  • Committee on Drugs, American Academy of Pediatrics. The transfer of drugs and other chemicals into human breast milk. Pediatrics 2001 108:776-89.
  • Flenady V, et al. 2013. Prophylactic antibiotics for inhibiting preterm labour with intact membranes. Cochrane Database Syst Rev. 5;12:CD000246.
  • Goldstein LH, et al. 2009. The safety of macrolides during lactation. Breastfed Med 4:157-200.
  • Källén B, Danielsson BR, 2014. Fetal safety of erythromycin. An update of Swedish data. Eur J Clin Pharmacol. 70(3):355-60.
  • Lin KJ, et al. 2013. Safety of macrolides during pregnancy. Am J Obstet Gynecol. 208(3):221.e1-8.
  • Lund M, et al. 2014. Use of macrolides in mother and child and risk of infantile hypertrophic pyloric stenosis: nationwide cohort study. BMJ. 11;348:g1908.
  • Marlow N, et al. 2017. The ORACLE Children Study: educational outcomes at 11 years of age following antenatal prescription of erythromycin or co-amoxiclav. Arch Dis Child Fetal Neonatal Ed;102(2):F131-F135.
  • Romøren M, et al. 2012. Pregnancy outcome after gestational exposure to erythromycin – a population-based register study from Norway. Br J Clin Pharmacol. 74(6):1053-62.
  • Sorensen, HT et al. 2003. Risk of infantile hypertrophic pyloric stenosis after maternal postnatal use of macrolides. Scand J Infect Dis. 35:104-6.
  • WHO Working Group, Bennet PN (ed) 1988: Drugs and Human Lactation. Elsevier, Amsterdam, New York, Oxford, Pp. 253-4.