Is Azithromycin (a macrolide antibiotic) safe during pregnancy?

From the Guidelines

Azithromycin is generally considered safe during pregnancy when medically necessary, as suggested by the most recent guidelines 1. The use of azithromycin in pregnant women is supported by evidence from various studies, including those focused on the management of hidradenitis suppurativa and airways diseases during pregnancy. According to the guidelines, in pregnant patients with hidradenitis suppurativa who require systemic antibiotics, azithromycin is suggested as a safe option 1. This recommendation is based on the available evidence, which indicates that azithromycin is classified as FDA pregnancy category B, meaning animal studies have not shown harm to the fetus, and there are no adequate well-controlled studies in pregnant women showing adverse effects. Some key points to consider when prescribing azithromycin during pregnancy include:

• The typical adult dose is 500 mg on day 1, followed by 250 mg daily for 4 more days for most infections, though single-dose regimens (1 gram) may be used for certain conditions like chlamydia.
• Untreated infections during pregnancy can pose serious risks to both mother and baby, including preterm birth, low birth weight, and transmission of infection to the newborn.
• As with any medication during pregnancy, azithromycin should only be used when clearly needed and prescribed by a healthcare provider who is aware of the pregnancy. It's also worth noting that other studies, such as those published in the European Respiratory Journal 1, support the use of azithromycin during pregnancy, citing its safety profile and effectiveness in treating various infections. However, it's essential to prioritize the most recent and highest-quality evidence, which in this case is the 2025 guideline on the medical management of hidradenitis suppurativa in special patient populations 1.

From the FDA Drug Label

PregnancyTeratogenic Effects. Pregnancy Category B Reproduction studies have been performed in rats and mice at doses up to moderately maternally toxic dose concentrations (i.e., 200 mg/kg/day). These doses, based on a mg/m2 basis, are estimated to be 4 and 2 times, respectively, the human daily dose of 500 mg. In the animal studies, no evidence of harm to the fetus due to azithromycin was found. There are, however, no adequate and well-controlled studies in pregnant women Because animal reproduction studies are not always predictive of human response, azithromycin should be used during pregnancy only if clearly needed.

Azithromycin use in pregnancy is categorized as Pregnancy Category B. While animal studies have shown no evidence of harm to the fetus, there are no adequate and well-controlled studies in pregnant women. Therefore, azithromycin should be used during pregnancy only if clearly needed 2.

From the Research

Safety of Azithromycin in Pregnancy

• The use of azithromycin in pregnancy has been studied, and the results are mixed 3.
• Some studies have reported increased risks of spontaneous miscarriage, major congenital malformations, cardiovascular malformations, digestive system malformations, preterm birth, and low birth weight associated with prenatal azithromycin exposure, while others have not found these associations 3.
• Azithromycin is categorized as pregnancy class B, and the data for risk of congenital malformations associated with its use during pregnancy ranges from no risk to a small increased risk 4.
• The benefits of azithromycin treatment during pregnancy should be weighed against the potential risks, especially for women with conditions such as cystic fibrosis who may require chronic azithromycin therapy 4.

Azithromycin Use in Pregnancy

• Azithromycin is commonly prescribed for the treatment of sexually transmitted diseases, toxoplasmosis, and malaria during pregnancy 3.
• It is also used in the management of preterm pre-labor rupture of membranes and as adjunctive prophylaxis for cesarean delivery 3.
• Azithromycin is an alternative to fluoroquinolones, which are contraindicated during pregnancy, for the treatment of gonorrhea and chlamydial infections 5.
• Azithromycin has been shown to be effective in eradicating Haemophilus ducreyi in patients with chancroid and is also used to treat trichomoniasis during pregnancy 5.

General Considerations

• Physiologic changes in pregnancy can lead to pharmacokinetic alterations in antibiotics, requiring dose adjustment or careful monitoring and assessment 6.
• Antibiotics such as beta-lactams, vancomycin, nitrofurantoin, metronidazole, clindamycin, and fosfomycin are generally considered safe and effective in pregnancy, while fluoroquinolones and tetracyclines are generally avoided 6.
• The treatment of sexually transmitted diseases during pregnancy is crucial to prevent adverse outcomes, and azithromycin is one of the options available for this purpose 5, 7.