What antibiotics are safe to use during pregnancy?

From the Guidelines

The safest antibiotics to use during pregnancy are penicillins, such as amoxicillin, and cephalosporins, such as cephalexin, as well as macrolides like azithromycin, which have established safety profiles with minimal risk to the developing fetus. According to the most recent guidelines 1, oral cephalexin and azithromycin are suggested for use in pregnant patients with hidradenitis suppurativa who require systemic antibiotics, due to evidence of their safety in pregnancy.

When considering antibiotic use during pregnancy, it's crucial to weigh the benefits of treating an infection against the potential risks to the fetus. Some antibiotics, like tetracyclines (e.g., doxycycline) and fluoroquinolones, should be avoided due to their potential to affect fetal bone and tooth development or other adverse effects 1. Trimethoprim, especially in the first trimester, is also recommended to be avoided due to potential increased risks of preterm birth, low birthweight, and kernicterus 1.

Key points to consider:

• Penicillins and cephalosporins are generally safe and often used as first-line treatments.
• Macrolides, like azithromycin, are also considered safe for use during pregnancy.
• Tetracyclines, fluoroquinolones, and trimethoprim should be avoided due to potential fetal risks.
• The safety of antibiotics can vary by trimester, with the first trimester being most critical for fetal development.
• Informing healthcare providers about pregnancy is crucial before taking any medication to ensure the benefits of treatment outweigh the risks.

In terms of specific recommendations, azithromycin and cephalexin are conditionally suggested for pregnant patients requiring systemic antibiotics 1, indicating their relatively safe profile compared to other options. However, the decision to use any antibiotic during pregnancy should be made under the guidance of a healthcare provider, considering the individual case and the most current evidence available.

From the FDA Drug Label

1. 1 Pregnancy Teratogenic Effects: Reproduction studies have been performed in mice and rats at doses up to 2000 mg/kg (3 and 6 times the 3 g human dose, based on body surface area). There was no evidence of harm to the fetus due to amoxicillin. There are, however, no adequate and well-controlled studies in pregnant women Because animal reproduction studies are not always predictive of human response, amoxicillin should be used during pregnancy only if clearly needed.

Amoxicillin can be used during pregnancy, but only if clearly needed, as there are no adequate and well-controlled studies in pregnant women 2.

• The decision to use amoxicillin during pregnancy should be made with caution, considering the potential benefits and risks.
• It is essential to weigh the need for amoxicillin against the potential risks to the fetus.
• Amoxicillin should only be used during pregnancy if the benefits outweigh the risks.

From the Research

Antibiotics Safe in Pregnancy

• The use of antibiotics during pregnancy is a common practice, with approximately one in four women being prescribed an antibiotic during pregnancy 3.
• Antibiotics such as beta-lactams, vancomycin, nitrofurantoin, metronidazole, clindamycin, and fosfomycin are generally considered safe and effective in pregnancy 3.
• Fluoroquinolones and tetracyclines are generally avoided in pregnancy due to potential risks to the fetus 3, 4.
• Penicillins, cephalosporins, and erythromycins have been documented to be safe for the fetus and are often used to treat susceptible infections during pregnancy 4.
• Aminoglycosides can be used safely if serum levels are carefully monitored in the mother 4.

Considerations for Antibiotic Use in Pregnancy

• Physiologic changes in pregnancy can lead to pharmacokinetic alterations in antibiotics, requiring dose adjustment or careful monitoring and assessment 3.
• The safety of newer antibiotics, such as azithromycin and clarithromycin, is not well established, and their use should be approached with caution 4.
• The first-line agents for the treatment of tuberculosis (i.e., INH, rifampin, and ethambutol) are considered safe in pregnancy 4.
• Antibiotics should not be withheld from pregnant women, especially when indicated for serious, life-threatening infections 5, 6.

Updates on Antibiotic Safety in Pregnancy

• A 2025 review provides an update on the safe use of antibiotics in pregnancy, including newly approved antibiotics and additional published evidence on previously reviewed antibiotics 7.
• Clinicians should remain updated on current available evidence and vigilant to provide safe and effective antibiotic decision-making in pregnant women 7.