Most common over-the-counter medications, including ibuprofen, acetaminophen, and many antihistamines, are safe to take while breastfeeding. The key factor is how much of a drug actually reaches your baby through breast milk. Pharmacologists measure this as the “relative infant dose,” and medications where the baby receives less than 10% of the mother’s weight-adjusted dose are generally considered safe. The majority of everyday medications fall well below that threshold.
Pain Relievers
Ibuprofen and acetaminophen are the two safest choices for pain and fever while breastfeeding. Both transfer into breast milk in very small amounts. Ibuprofen reaches its peak concentration in milk about one to two hours after you take it, but even at peak levels, your baby gets a tiny fraction of the dose. Either one can be used at standard doses for headaches, cramps, muscle pain, or postpartum soreness.
Aspirin is a different story. At regular doses it can accumulate in an infant’s system and has been linked to a rare but serious condition called Reye’s syndrome in children. An occasional low-dose aspirin (like a baby aspirin for heart health) is generally not a concern, but for routine pain relief, stick with ibuprofen or acetaminophen.
Codeine and tramadol should be avoided entirely. The FDA has issued a specific warning against using either drug while breastfeeding. Some people metabolize codeine into morphine much faster than normal, which can cause dangerously high levels of morphine in breast milk. Because there’s no easy way to know if you’re one of those fast metabolizers, and because early signs of opioid overdose in an infant (extreme sleepiness, difficulty feeding, breathing problems) can be hard to spot, the risk isn’t worth taking.
Allergy and Cold Medications
For seasonal allergies or hives, cetirizine (Zyrtec) and loratadine (Claritin) are the preferred antihistamines during breastfeeding. Both are non-sedating, and the amount that passes into milk is low. There have been occasional reports of reduced milk supply with either one, but at normal doses, they’re unlikely to affect production once breastfeeding is well established (typically after the first six to eight weeks). If you’re still in those early weeks and notice a dip in supply, it’s worth flagging to your healthcare provider.
Older, sedating antihistamines like diphenhydramine (Benadryl) transfer more readily and can make your baby drowsy. They’re not strictly off-limits for a one-time dose, but the newer options are a better routine choice.
The bigger risk in the cold-medicine aisle is pseudoephedrine, the decongestant in original Sudafed. Research has shown it can lower milk supply after just a single tablet. If you’re congested, saline nasal spray or a steroid nasal spray are safer alternatives that don’t affect production. Phenylephrine, the other common decongestant, is poorly absorbed and unlikely to work well for you or harm your baby, but it’s also unlikely to help much.
Antibiotics
Most commonly prescribed antibiotics are compatible with breastfeeding. Amoxicillin and cephalexin (Keflex) both pass into milk in only tiny amounts. The most common side effect you might notice in your baby is loose stools or, less often, oral thrush (white patches in the mouth from a yeast imbalance). These are usually mild and resolve once you finish the course. They’re not a reason to stop breastfeeding or skip antibiotics you need.
Penicillins, cephalosporins, and macrolides like azithromycin are all generally well-tolerated. If your doctor prescribes an antibiotic and you’re breastfeeding, it’s reasonable to ask whether it’s one of the commonly used options with good safety data in nursing mothers, but most are.
Heartburn and Acid Reflux Medications
Antacids like calcium carbonate (Tums) are fine since they aren’t absorbed into your bloodstream in meaningful amounts. For stronger relief, both H2 blockers and proton pump inhibitors (PPIs) can be used while breastfeeding.
Among H2 blockers, famotidine (Pepcid) is preferred because smaller amounts pass into milk compared to cimetidine (Tagamet). For PPIs, omeprazole (Prilosec) and pantoprazole are the top choices. They’re excreted into breast milk in very small quantities, and any PPI that does reach the milk is likely broken down by your baby’s stomach acid before it can be absorbed. So even the small amount that transfers is functionally inactive by the time it reaches your infant’s system.
Antidepressants and Anxiety Medications
Untreated depression or anxiety during the postpartum period carries real risks for both you and your baby, and several antidepressants have strong safety data in breastfeeding. Sertraline (Zoloft) and paroxetine (Paxil) consistently produce undetectable levels in infant blood samples. A pooled analysis published in the American Journal of Psychiatry found that across dozens of cases, sertraline and paroxetine rarely resulted in measurable infant blood levels at all. Both are considered preferred choices for breastfeeding mothers who need an antidepressant.
Fluoxetine (Prozac) is more variable. It has a long half-life, meaning it lingers in the body longer, and infant blood levels are less predictable. It’s not off-limits, but if you’re starting a new antidepressant while nursing (rather than continuing one that already works for you), sertraline is typically the first option discussed.
If you’re on medication for anxiety or depression and considering breastfeeding, the conversation should focus on finding what works for your mental health with the best safety profile, not on whether to medicate at all. Stopping a medication that’s keeping you well can be riskier than the small amount your baby might receive through milk.
Vaccines
Vaccines are safe to receive while breastfeeding. This includes both inactivated vaccines (like flu shots and Tdap) and live vaccines (like MMR). The CDC confirms that it’s safe for mothers to receive vaccines right after giving birth, even while breastfeeding. You don’t need to pump and dump or delay a feeding after getting vaccinated.
Timing Doses to Reduce Exposure
For most safe medications, timing doesn’t matter much because the amount reaching your baby is already negligible. But if you want to minimize exposure further, the general strategy is straightforward: take your medication right after a feeding session, then wait two to three hours before nursing again. Drug levels in breast milk mirror drug levels in your blood, so by the time the medication peaks and begins to decline, your next feeding falls in a lower-exposure window.
This approach works best with medications that have a short half-life, meaning they’re processed and cleared from your body relatively quickly. For drugs that stay in your system for a long time, like fluoxetine, timing individual doses around feedings won’t make a meaningful difference because the drug level stays relatively constant.
Medications to Avoid
A short list of medications should be clearly avoided while breastfeeding:
- Codeine and tramadol: Risk of infant opioid toxicity due to unpredictable metabolism.
- Pseudoephedrine: Can significantly reduce milk supply, sometimes after a single dose.
- Chemotherapy drugs and immunosuppressants: These are designed to affect rapidly dividing cells and can be harmful to infants.
- Radioactive compounds: Used in certain diagnostic imaging. You’ll be told to temporarily stop breastfeeding if these are necessary.
- High-dose aspirin: Regular analgesic doses pose risks; occasional low-dose aspirin is generally acceptable.
Medications where the relative infant dose exceeds 25% of the maternal dose are considered unsafe for breastfeeding. Most common over-the-counter and prescription drugs fall far below this level, which is why the overall message is reassuring: the list of medications you can safely take while nursing is much longer than the list you need to avoid.