Many new mothers worry: Can I take this medication while breastfeeding? The fear isn’t irrational-every pill you swallow could end up in your baby’s system. But here’s the truth: most medications are safe during breastfeeding. In fact, the vast majority of drugs pass into breast milk in tiny, harmless amounts. The bigger risk isn’t the medicine-it’s stopping breastfeeding because you were told to, when you didn’t need to.
According to the American Academy of Pediatrics and the CDC, up to 15% of mothers stop breastfeeding early because of misinformation about medications. Not because the drugs were dangerous, but because their doctor, pharmacist, or even well-meaning friend said, "Better safe than sorry." That’s unnecessary. With the right information, you can manage your health and keep feeding your baby.
Pain Relief: What’s Safe and What’s Not
Postpartum pain is common. Whether it’s from a C-section, episiotomy, or just general soreness, you need relief. The good news? Two over-the-counter options are considered gold standards: acetaminophen (Tylenol) and ibuprofen (Advil, Motrin IB).
Both have extremely low transfer rates into breast milk. Acetaminophen’s Relative Infant Dose (RID)-a measure of how much the baby actually absorbs-is only 0.04% to 0.23%. Ibuprofen is a bit higher at 0.38% to 1.85%, but still safe. Neither has been linked to any adverse effects in infants, even with long-term use. The American Academy of Family Physicians specifically recommends them because they’re safe for babies to take directly-and if it’s safe for a baby to swallow, it’s almost always safe through breast milk.
What about naproxen (Aleve)? It’s okay for occasional use, but not long-term. Its half-life is 12-17 hours, meaning it builds up. There are rare case reports of infants developing anemia, vomiting, or bleeding issues with prolonged exposure. Stick to ibuprofen or acetaminophen unless your doctor says otherwise.
For stronger pain, opioids are tricky. Codeine is off-limits. The FDA issued a black box warning in 2010 because some mothers metabolize it too quickly, turning it into dangerous levels of morphine in their milk. Morphine and hydromorphone, however, are acceptable at the lowest effective dose for the shortest time-especially if you’re monitoring your baby for drowsiness or trouble feeding.
Antibiotics: Common Prescriptions, Clear Guidelines
Postpartum infections-mastitis, uterine infections, or even a simple UTI-are common. You need antibiotics, and you need them fast. The good news? Most are safe.
Penicillins like amoxicillin are first-line. Their RID is 0.3%-1.5%, and there are zero documented cases of harm to breastfed infants. Same with cephalosporins like cephalexin. Vancomycin doesn’t absorb well in the gut, so even if it gets into milk, your baby won’t absorb it. These are all classified as "safest for administration" by the AAFP.
Macrolides like azithromycin are also safe. Its RID is just 0.05%-0.1%. Erythromycin is okay too, but there’s a tiny theoretical risk of infant pyloric stenosis-a rare condition that causes vomiting. If you’ve had a baby with this before, talk to your doctor. For most, azithromycin is the better pick.
Fluoroquinolones like ciprofloxacin have an RID of 0.5%-1.0%. Animal studies raised concerns about cartilage damage, but in over 30 years of use in breastfeeding mothers, no infant has shown any joint or bone issues. The AAFP says it’s safe with monitoring.
Doxycycline? It’s a tetracycline, so you’ve probably heard it’s risky. But here’s the twist: short courses (under 21 days) are considered acceptable. The RID is 1.5%-2.5%, but no cases of tooth discoloration have ever been documented in breastfed babies. Long-term use? Avoid it. Short-term? Fine.
Psychiatric Medications: Managing Mental Health While Nursing
Postpartum depression affects 1 in 7 mothers. Untreated, it can harm bonding, sleep, and even infant development. The good news? There are safe, effective options.
Sertraline (Zoloft) is the most studied and recommended SSRI for breastfeeding. Its RID is 1.7%-7.0%, but infant blood levels are often undetectable. Multiple studies show no developmental delays or behavioral issues in children exposed through breast milk.
Paroxetine (Paxil) is also safe, with an RID of 1.2%-10.0%. It’s slightly more likely to cause drowsiness in infants, but still considered first-line.
Fluoxetine (Prozac)? Use with caution. It has a half-life of 4-6 days. That means it builds up over time. One 2021 study found 2% of exposed infants had irritability or poor feeding. If you’re on fluoxetine and your baby seems unusually fussy or sleepy, talk to your doctor about switching to sertraline.
For anxiety, lorazepam (Ativan) is the preferred benzodiazepine. It has a short half-life (10-20 hours) and low RID (0.05%-1.0%). Clonazepam (Klonopin)? Avoid it for regular use. Its half-life is 30-40 hours, so it lingers. Use only in emergencies.
Antipsychotics like quetiapine (Seroquel) and risperidone (Risperdal) are also safe at standard doses. Long-term follow-up studies show normal growth and development in infants exposed through breast milk.
Allergy and Cold Medications: Don’t Let Symptoms Win
Allergies and colds don’t take a break after baby arrives. But not all meds are created equal.
Nasal corticosteroids like fluticasone (Flonase) and budesonide (Rhinocort) are ideal. Less than 0.9% of the dose enters your bloodstream, so almost nothing reaches your milk. No risk to baby.
For oral antihistamines, stick to second-generation options: loratadine (Claritin), cetirizine (Zyrtec), and fexofenadine (Allegra). All have RIDs under 0.5% and no documented side effects in infants. You can take them daily without worry.
First-generation antihistamines like diphenhydramine (Benadryl)? Avoid them. They cross into milk more easily (RID 1.0%-2.0%) and can make babies sleepy or irritable. One study found 5% of exposed infants showed signs of sedation.
And here’s the big one: pseudoephedrine (Sudafed). It’s a decongestant, yes-but it also cuts milk supply by 24% on average. Some women see a dramatic drop. The AAFP recommends saline sprays, humidifiers, and steam instead. If you must use it, take it after a feeding, and watch your supply closely.
When Medications Are Not Safe
There are exceptions. And they matter.
Radioactive iodine (I-131) for thyroid cancer? You must stop breastfeeding permanently. It concentrates in breast milk and can destroy your baby’s thyroid. The AAFP says breastfeeding must stop for 3-6 weeks after treatment.
Lithium for bipolar disorder? It’s tricky. Infant lithium levels can reach 30%-50% of maternal levels. It’s not forbidden, but you need weekly blood tests on your baby to keep levels below 0.6 mmol/L. If monitoring isn’t possible, alternatives like lamotrigine are preferred.
Anticancer drugs like chemotherapy? Almost always require stopping breastfeeding. These drugs are designed to kill fast-growing cells-your baby’s developing cells are too vulnerable. Work with your oncologist to find safe alternatives or plan for pumping and discarding milk during treatment.
What to Do When You’re Unsure
You don’t have to guess. There are trusted, free, evidence-based tools built for this exact situation.
LactMed, from the U.S. National Library of Medicine, is the gold standard. It has data on over 1,000 drugs, including exact RID values, milk-to-plasma ratios, and documented infant effects. It’s updated quarterly. Use it before you take anything new.
InfantRisk Center (infantrisk.com) offers real-time advice from experts. They handle over 15,000 calls a year from moms and providers. Call or text them with the name of your medication-they’ll give you a risk assessment within minutes.
MotherToBaby provides personalized counseling through regional centers. They’ve studied over 1,200 breastfeeding medication exposures and publish their findings in peer-reviewed journals.
Remember: If a medication is approved for direct use in infants, it’s almost always safe in breast milk. But always check. Don’t rely on memory, old advice, or a quick Google search.
Final Takeaway: You Can Do Both
Being a mom means making hard choices. But you don’t have to choose between your health and your baby’s nutrition. With accurate, evidence-based information, you can treat your condition and keep breastfeeding.
Don’t let fear or outdated advice make you stop. Talk to your provider. Use LactMed. Ask the InfantRisk Center. And know this: millions of mothers have taken medications while breastfeeding-and their babies are healthy, thriving, and still nursing.