Can azithromycin be prescribed to a woman at 11 weeks gestation?

Azithromycin Use at 11 Weeks Gestation

Yes, azithromycin can be safely prescribed to a pregnant woman at 11 weeks gestation when clinically indicated. 1, 2

Safety Classification and Regulatory Status

• The CDC specifically designates azithromycin as the preferred macrolide antibiotic during pregnancy, including the first trimester, based on its superior safety profile. 1, 2
• The FDA classifies azithromycin as Pregnancy Category B, meaning animal reproduction studies at doses up to 4 times (rats) and 2 times (mice) the human daily dose of 500 mg showed no evidence of fetal harm. 3
• No conclusive evidence exists that azithromycin use during pregnancy causes adverse fetal outcomes, according to CDC guidance. 1, 2
• A prospective cohort study of 123 pregnant women found no statistically significant increase in major malformations (3.4% in exposed group vs. 2.3% in disease-matched controls), with 71.6% of exposures occurring during the first trimester. 4

Approved Clinical Indications During Pregnancy

• Chlamydial infections: 1g orally as a single dose 5, 2
• Community-acquired pneumonia and atypical pneumonia (Mycoplasma, Chlamydia, Legionella): 500mg day 1, then 250mg daily for days 2-5 2, 6
• Pertussis treatment or prophylaxis, particularly in the third trimester 2
• Gonococcal conjunctivitis: 1g orally as a single dose (in combination with ceftriaxone 250mg IM) 5

Critical Safety Distinction: Do Not Substitute Clarithromycin

• Never substitute clarithromycin for azithromycin during pregnancy—clarithromycin has demonstrated teratogenic effects in animal studies and is classified as DIII (should not be used) by the CDC. 2, 6
• Azithromycin and clarithromycin are not interchangeable despite both being macrolides. 1, 2

Common Pitfalls to Avoid

• Do not withhold azithromycin in the first trimester out of excessive caution when treatment is clinically indicated—this approach is not evidence-based. 1
• Pregnant women should not be treated with doxycycline, quinolones, or tetracyclines due to fetal tooth discoloration, bone effects, and hepatotoxicity risk. 5, 2
• Monitor for standard azithromycin adverse effects: QT prolongation, hepatotoxicity, and Clostridium difficile-associated diarrhea. 2, 3
• If treating pneumonia after 20 weeks gestation, monitor for preterm labor as pneumonia itself increases this risk. 2

Alternative Antibiotics if Azithromycin Cannot Be Used

• Erythromycin is an acceptable macrolide alternative, though it causes more gastrointestinal side effects and has a 38.8% rate of severe side effects requiring medication change compared to 7.4% with azithromycin. 2, 7
• Amoxicillin is the safest first-line choice for typical bacterial lower respiratory tract infections throughout pregnancy. 2