When you’re breastfeeding and get sick, the last thing you want is to choose between getting better and keeping your baby fed. Many new parents hear conflicting advice - some say to stop nursing, others say it’s fine. The truth? Most antibiotics are safe to take while breastfeeding. You don’t need to pump and dump unless your doctor specifically says so. But knowing which ones are safe - and which ones to avoid - makes all the difference.
Why This Matters More Than You Think
About 94% of breastfeeding parents need to take medication at some point after giving birth. Antibiotics make up more than half of those prescriptions. Yet, nearly half of all moms who are prescribed antibiotics stop breastfeeding unnecessarily because they’re afraid it will harm their baby. That’s not just sad - it’s avoidable. The good news? Decades of research, updated as recently as 2023, show that most common antibiotics pass into breast milk in tiny amounts - too small to hurt your baby. In fact, many of these same drugs are given directly to newborns in hospitals. If it’s safe for a 2-day-old infant to take, it’s almost certainly safe for them to get through breast milk.The Safest Antibiotics: L1 Category
These are the go-to choices for breastfeeding moms. They’re labeled L1 - the safest category - based on decades of data from pharmacokinetic studies and real-world use. They transfer less than 0.1% of the mother’s dose into milk, and no serious side effects have been reported in thousands of cases.- Penicillins - Amoxicillin and ampicillin are the most common. Used for ear infections, sinus infections, strep throat, and mastitis. Milk transfer is only about 0.03%. Zero documented adverse effects in over 2,000 infant cases.
- Cephalosporins - Cephalexin and ceftriaxone are equally safe. They’re often used when someone is allergic to penicillin. Transfer rate is around 0.05%. One note: ceftriaxone’s longer half-life means extra caution is advised for preterm babies due to rare bilirubin displacement risks.
- Vancomycin - Used for serious infections like MRSA. It’s poorly absorbed by the baby’s gut, so even though it shows up in milk, it doesn’t get into their bloodstream. Safe for full-term and preterm infants.
Still Generally Safe: L2 Category
These antibiotics are also considered compatible with breastfeeding, but they transfer slightly more into milk. Still, no major risks have been proven - and benefits usually outweigh any small potential downsides.- Azithromycin - A macrolide often used for respiratory infections. Milk transfer is low (0.3%). Preferred over erythromycin, which has a higher risk of causing infant pyloric stenosis.
- Erythromycin - Can be used, but avoid if possible. Studies show a 15% increased chance of infant pyloric stenosis (a rare but serious stomach condition). If your doctor prescribes this, ask if azithromycin is an option.
- Fluconazole - Used for yeast infections (like thrush). It transfers fully into milk, but no harmful effects have been seen in over 1,800 documented cases. In fact, it’s often used to treat thrush in babies directly.
Use With Caution: L3 Category
These antibiotics are not ideal, but they may still be necessary. If your infection is serious and no safer option works, your doctor may still prescribe them - but you’ll need to watch your baby closely.- Clindamycin - One of the riskiest common antibiotics for breastfeeding. It transfers at 1.5-3% and causes infant diarrhea in up to 18% of cases. One mom on BabyCenter reported her baby developed bloody stools after three days on clindamycin - confirmed by the pediatrician as antibiotic-related. If you must take it, monitor stool frequency and consistency. Probiotics may help.
- Metronidazole - Often used for bacterial vaginosis or C. diff. Transfer is low (0.5-1%), but it’s linked to a 5% increase in yeast infections in babies. The NHS used to recommend pumping and discarding milk for 12-24 hours after a single 2g dose - but newer data shows this isn’t needed for standard 500mg doses. You can keep breastfeeding.
- Doxycycline - A tetracycline. Long-term use (over 21 days) can cause tooth discoloration in infants. But short courses (7-14 days) are now considered safe by the NHS and AAP. Use only if no other option exists.
Antibiotics to Avoid
These are not safe for breastfeeding. Even small amounts can cause serious harm.- Chloramphenicol - Linked to “gray baby syndrome,” a rare but fatal condition in newborns. Never use while breastfeeding.
- Nitrofurantoin - Avoid if your baby is under 1 month or has G6PD deficiency (common in African American and Mediterranean infants). Can cause hemolytic anemia. Alternative antibiotics exist for UTIs.
- Trimethoprim/sulfamethoxazole (Bactrim) - Avoid if your baby is under 2 months, especially if they have jaundice. This combo can displace bilirubin and increase the risk of kernicterus - a type of brain damage. Safe for term infants over 2 months, but not before.
How to Minimize Baby’s Exposure
Even with safe antibiotics, you can reduce your baby’s exposure even further:- Take the dose right after breastfeeding. This lets your body clear the drug before the next feeding. Studies show this reduces infant exposure by 30-40%.
- Watch for changes. Look for loose stools, fussiness, rashes, or signs of thrush (white patches in the mouth). Most side effects are mild and go away after stopping the antibiotic.
- Don’t stop breastfeeding unless advised. Stopping breastfeeding because of an antibiotic is rarely necessary - and often does more harm than good. Your milk protects your baby from infections.
What to Do If Your Baby Has a Reaction
Most reactions are mild - like a few extra loose stools or mild diaper rash. But if your baby develops:- Diarrhea with blood or mucus
- Refusal to feed
- Unusual sleepiness or irritability
- Yellowing skin that gets worse
Tools and Resources You Can Trust
Don’t guess. Use reliable tools:- LactMed - A free database from the NIH. Updated in 2023, it covers over 1,700 medications with detailed safety data. Available as a website or app (4.7/5 stars).
- InfantRisk Center - Call 806-352-2519. They answer questions 24/7. In 2022 alone, they handled over 1,200 calls about antibiotics.
- AAFP Medication Safety Cards - Many doctors now give out printed cards listing safe antibiotics. Ask for one.
What Doctors Are Saying
Experts agree: penicillins and cephalosporins are the gold standard. Dr. Thomas Hale, who created the Lactation Risk Category system, says: “All penicillins have L1 status with negligible transfer - they’re ideal for lactating patients.” The American College of Obstetricians and Gynecologists (ACOG) recommends them as first-line for all common infections in breastfeeding women. Even the NHS, which used to be more cautious, now says most antibiotics are safe - as long as you pick the right one.What’s Changing in 2025?
New antibiotics like tedizolid (L2) and delafloxacin (L3) are being added to safety lists. Hospitals are now required to track breastfeeding compatibility as part of antibiotic stewardship programs. And thanks to pressure from parents, drug labels now include lactation info - something that wasn’t required until 2021. The bottom line? You don’t have to choose between your health and your baby’s. With the right antibiotic, you can treat your infection and keep nursing without worry.Can I breastfeed while taking amoxicillin?
Yes, amoxicillin is one of the safest antibiotics for breastfeeding. It transfers less than 0.03% of your dose into breast milk. Thousands of babies have been exposed without any reported side effects. You can continue breastfeeding normally.
Will antibiotics hurt my baby’s stomach?
Some antibiotics, like clindamycin, can cause loose stools or diarrhea in babies because they affect gut bacteria. This is usually mild and temporary. Probiotics may help. If your baby has bloody stools, fever, or refuses to feed, contact your pediatrician - but don’t stop breastfeeding unless told to.
Should I pump and dump after taking antibiotics?
Almost never. Pumping and dumping is only recommended for a few specific drugs, like a single high dose of metronidazole - and even that’s no longer required by most guidelines. For 95% of antibiotics, including amoxicillin, azithromycin, and cephalexin, you can keep breastfeeding without interruption.
Is Bactrim safe while breastfeeding?
Trimethoprim/sulfamethoxazole (Bactrim) should be avoided if your baby is under 2 months old, especially if they have jaundice or are premature. It can increase the risk of kernicterus, a serious condition. For babies over 2 months and healthy, it’s generally considered safe. Always check with your doctor.
What if I’m allergic to penicillin?
Cephalosporins like cephalexin are usually safe alternatives. Cross-reactivity is rare - less than 10% of people with penicillin allergies react to cephalosporins. Azithromycin is another good option. Always tell your doctor about your allergy so they can pick the right drug.