Is Z-Pack safe during pregnancy?

What does the evidence say about Z-Pack during pregnancy?

1. Azithromycin, known as the Z-Pack, is a prescription antibiotic your provider might choose during pregnancy for infections like pneumonia, bronchitis, strep throat, sinus infections, or chlamydia, weighing that against the risk of an untreated infection. 1
2. One large study looking at macrolide antibiotics found that azithromycin and clarithromycin weren't linked to a higher chance of heart defects or a stomach-muscle condition called pyloric stenosis. 2
3. A Quebec-based study of more than 135,000 pregnancies found azithromycin use in the first trimester wasn't statistically linked to a higher rate of major birth defects or heart-related malformations. 3
4. One large study did flag a small statistical increase in major malformations tied to first-trimester azithromycin use, though the related heart-defect finding was borderline and less certain. 4
5. The largest and most recent look at this, covering over 140,000 pregnancies exposed to macrolide antibiotics like azithromycin, found no overall increase in major birth defects compared with amoxicillin, a common and well-studied alternative. 5

Is Z-Pack safe in each trimester?

• First trimester. Most of the research on azithromycin and birth defects looks at first-trimester use, since that's when a baby's organs are forming. Large studies mostly haven't found a higher overall risk, though one study flagged a small statistical signal for major malformations that didn't hold up as clearly for heart-specific defects. If your provider prescribes a Z-Pack now, they've weighed that data against your specific infection.
• Second trimester. Second-trimester data on azithromycin is reassuring, though there's less of it since most studies focus on first-trimester exposure. Your provider may still reach for it here for a bacterial infection like pneumonia, a sinus infection, or a confirmed case of chlamydia.
• Third trimester. Third-trimester safety data on azithromycin is thinner than first-trimester data, but nothing in the research reviewed here points to a late-pregnancy-specific concern. If it's prescribed this late, it's typically a short course, and it's worth asking your provider how it fits with your delivery plan.