Is amoxicillin safe while breastfeeding?

What does the evidence say about amoxicillin while breastfeeding?

1. Amoxicillin passes into breast milk in only small amounts. The relative infant dose stays below 0.4 percent of a weight-adjusted maternal dose, and it is considered acceptable during breastfeeding since it produces milk levels not expected to cause adverse effects in nursing infants. 1
2. In published follow-up studies, mild diarrhea was the most-reported infant reaction, seen in a minority of infants (3 of 25 in one study, 2 of 40 in another), with occasional rash and, less commonly, oral thrush. A controlled prospective study found no statistical difference in these outcomes compared with infants of mothers not taking the antibiotic. 1
3. In a study following 323 term infants, where 68 percent of prescribed antibiotics were amoxicillin or amoxicillin-clavulanate, gut bacteria showed only a temporary dip in Bifidobacterium bifidum in the first two weeks after starting the antibiotic, and this difference did not persist a month later. Breastfeeding itself had a far larger, more consistently beneficial effect on the infant gut microbiome than the antibiotic exposure did. 2
4. Penicillin-class antibiotics, the drug family amoxicillin belongs to, pass into milk only in small amounts and are not expected to cause side effects in most infants, though providers advise watching for diarrhea, mouth pain, or white spots in the mouth that could point to thrush. 3
5. When amoxicillin is combined with clavulanic acid (as in Augmentin), a study of 67 breastfeeding infants found no serious side effects, with only temporary rash, diarrhea, irritability, or constipation reported in some babies. 4

How amoxicillin changes by nursing stage

• Early weeks. Early nursing. This is when amoxicillin often comes up, for a UTI, mastitis, or a dental infection in the days or weeks after birth. Watch your baby for loose stools or a rash, and call your pediatric provider if anything seems off.
• Established nursing. The same low-transfer picture holds for a sinus infection, strep throat, or another bacterial infection later on. A short course is not a reason to pause breastfeeding.
• Weaning. Weaning or occasional nursing. Less milk overall means even less of the drug passes through. If your baby has ever reacted to a penicillin-class antibiotic directly, mention that to your prescriber before you start amoxicillin yourself.