Can You Take Antibiotics While Breastfeeding? Amoxicillin, Cephalexin and More

When you’re sick and nursing, getting a prescription can bring a new worry: will the medicine hurt your baby? If your doctor has prescribed an antibiotic for a urinary tract infection, strep throat, mastitis, a dental infection or something else, you’ll be glad to know that most common antibiotics are considered compatible with breastfeeding.

This guide explains what the evidence says about the antibiotics nursing mothers are most often prescribed, what side effects to watch for in your baby, and the few situations that call for extra care. It’s general information, not a substitute for advice from your doctor or pharmacist, who can look at your exact medicine, dose and baby. For the bigger picture on medicines and milk, see our hub on what’s safe while breastfeeding.

Are antibiotics safe while breastfeeding?

For most people, yes. The CDC says it is usually safe to use prescription medicines while breastfeeding, and it points to a 2013 American Academy of Pediatrics report that found most medicines are safe during lactation. When your provider chooses a drug, the CDC says they weigh things like how much passes into milk, how well a baby absorbs it by mouth, possible side effects and your baby’s age.

For the antibiotics nursing mothers are most often prescribed, LactMed describes the amounts in breast milk as low. Some, such as azithromycin, are also given directly to babies as medicine in higher doses than a breastfed baby would ever get through milk.

The main source for the details below is LactMed, the National Library of Medicine’s database on drugs and breastfeeding, which the CDC recommends for drug-specific questions.

Common antibiotics at a glance

Antibiotic	What LactMed says	Notes
Amoxicillin	Low milk levels; acceptable in nursing mothers	Rash, diarrhea or thrush occasionally reported in babies
Amoxicillin-clavulanate (Augmentin)	Infant reactions uncommon; acceptable	Watch for restlessness, diarrhea and rash
Cephalexin (Keflex)	Low milk levels; acceptable; an alternative for mastitis	One rare severe allergic reaction reported in an infant previously exposed to cefazolin
Dicloxacillin	Very low milk levels; acceptable; frequently used for mastitis	Diarrhea or thrush occasionally reported with penicillins
Azithromycin (Zithromax)	Low milk levels; not expected to cause problems	Watch for vomiting, diarrhea, thrush or diaper rash
Doxycycline	Short courses unlikely to cause harm	Avoid courses longer than 21 days or repeat courses, as a precaution
Ciprofloxacin (Cipro)	Low milk levels; acceptable with monitoring	Waiting 3 to 4 hours after a dose to nurse lowers the baby’s exposure
Metronidazole (Flagyl)	Acceptable for usual doses, with some debate	Some sources advise a 12 to 24 hour pause after a single 2-gram dose
Nitrofurantoin (Macrobid)	Low milk levels; fine with older babies	Other drugs preferred under 8 days of age or with G6PD deficiency
Clindamycin (oral)	Not a reason to stop breastfeeding	An alternative may be preferred because of effects on baby’s gut

The antibiotics you’re most likely to be prescribed

Amoxicillin and amoxicillin-clavulanate

Amoxicillin is one of the most common antibiotics of all. LactMed says it produces low levels in milk that aren’t expected to cause problems for breastfed babies, and it calls amoxicillin acceptable in nursing mothers. The NHS agrees that it’s OK to take while breastfeeding because only tiny amounts get into breast milk.

Amoxicillin combined with clavulanic acid (often sold as Augmentin) is also considered acceptable. LactMed says infant reactions are uncommon and suggests watching for restlessness, diarrhea and rash.

Cephalexin and dicloxacillin

Cephalexin is a cephalosporin antibiotic, and LactMed lists it as an alternative for treating mastitis. Dicloxacillin, a penicillin-type antibiotic, is frequently used for mastitis too. Both are rated acceptable during breastfeeding. If you’re dealing with a painful, red breast, our guide to mastitis explains when antibiotics are needed and what else helps.

Azithromycin

Because milk levels are low and babies are given it directly in higher doses, LactMed says it would not be expected to cause problems in breastfed infants. It recommends watching for gut-related effects such as vomiting, diarrhea and thrush.

Antibiotics that need a closer look

Doxycycline and other tetracyclines

You may have read that tetracyclines are off-limits while nursing because they can stain a child’s teeth. LactMed says a close look at the evidence suggests short-term doxycycline is unlikely to cause harm, because milk levels are low and the calcium in breast milk reduces how much the baby absorbs. As a theoretical precaution, it advises avoiding courses longer than 21 days or repeated courses while nursing.

Ciprofloxacin

Fluoroquinolones such as ciprofloxacin have traditionally been avoided in babies because of concerns about developing joints, but LactMed says studies indicate little risk and calls it acceptable with monitoring. If you want to lower your baby’s exposure further, LactMed notes that waiting 3 to 4 hours after a dose before breastfeeding should help. Ask your doctor whether that makes sense for you.

Metronidazole

With metronidazole (Flagyl), babies do receive measurable amounts through milk, though less than the doses used to treat infants. Because of laboratory and animal findings, some experts are cautious about long courses. LactMed says some sources recommend stopping breastfeeding for 12 to 24 hours after a single 2-gram dose, but not after lower doses. Topical metronidazole, such as creams for rosacea, is considered acceptable. One vaginal product’s manufacturer advises not breastfeeding during treatment and for 2 days afterward, so check the leaflet and ask your pharmacist.

If your doctor does recommend a short pause, you can keep your supply going by pumping or hand expressing breast milk during that time.

Nitrofurantoin and clindamycin

For nitrofurantoin, LactMed says milk levels are low and it can be used with older babies, but other drugs are preferred if your baby is under 8 days old or has G6PD deficiency, an inherited condition that affects red blood cells. Oral clindamycin isn’t a reason to stop breastfeeding, but LactMed notes an alternative may be preferred because of its potential effects on a baby’s gut bacteria.

What to watch for in your baby

Antibiotics can change the normal bacteria in your baby’s gut, just as they can in yours. LactMed and the NHS mention these possible effects:

• Loose stools or diarrhea. Breastfed baby poop is normally soft, so look for a clear change from usual. Our baby poop color chart shows what’s typical.
• Thrush. White patches in the mouth that don’t wipe away, or a red diaper rash that won’t clear. Our guide to thrush while breastfeeding covers symptoms in both of you.
• Rash.
• Fussiness, poor feeding or unusual sleepiness.

LactMed points out that many of these effects haven’t been well studied, and most are mild. Rarely, with clindamycin, blood in the stool could signal a more serious gut problem.

Tips for taking antibiotics while nursing

1. Tell every prescriber you’re breastfeeding, including dentists and urgent care. There’s often more than one good choice.
2. Finish the course as prescribed, unless your doctor tells you otherwise.
3. Keep feeding as usual. For most antibiotics there’s no need to pump and dump.
4. Mention your baby’s age and health. A newborn, a premature baby or a baby with a known condition may change which drug is best.
5. Ask about pain relief too. If you need something for fever or pain, see our guide to ibuprofen and Tylenol while breastfeeding. Our article on breastfeeding while sick covers colds, flu and stomach bugs.

When to call your doctor or your baby’s doctor

Call your baby’s doctor if your baby:

• has diarrhea, is vomiting or isn’t feeding as well as usual,
• has white patches in the mouth or a diaper rash that won’t go away,
• develops a rash, seems unusually sleepy, or
• has blood in the stool.

Call your own doctor if your symptoms aren’t improving as expected, you develop a rash or other side effects, or you have a fever with a red, painful area on your breast. The NHS advises that, until you get advice, you keep taking the medicine and keep breastfeeding as usual. If you’re unsure about a particular drug, a pharmacist or an IBCLC can help, and our breastfeeding support page lists where to find them.