Cough and Allergy Medications During Lactation: What You Need to Know About Infant Sedation Risks

When you're breastfeeding and hit with a cold or allergies, the last thing you want is to choose between feeling better and keeping your baby safe. Many moms assume that if a medicine is available over the counter, it's automatically safe for nursing. But that’s not true. Some common cough and allergy meds can make your baby dangerously sleepy-or worse. The truth is, a single dose of certain medications can lead to serious side effects in newborns, especially those under two months old. Your body doesn’t just filter out the bad stuff. Some drugs pass right into your breast milk, and your baby’s tiny liver isn’t built to handle them.

Why Some Medications Are Riskier Than Others

Not all medications behave the same way in breast milk. What matters isn’t just the drug itself, but how your body processes it and how your baby’s body reacts. For example, dextromethorphan, the main ingredient in many cough syrups, barely makes it into breast milk-only about 0.1% of the dose you take. That’s why it’s considered one of the safest options for nursing moms. On the other hand, codeine, once a common go-to for pain and cough, is now flagged as a serious risk. The FDA issued a black box warning in 2017 after multiple cases of infant deaths linked to codeine use during breastfeeding. Why? Because some people are ultra-rapid metabolizers-about 1 in 100 Caucasians-and their bodies turn codeine into morphine way too fast. That morphine ends up in breast milk, and babies can’t process it. One study found infant blood levels of morphine reached up to 30 ng/mL after a standard maternal dose. That’s enough to shut down breathing in a newborn.

First-Generation Antihistamines: The Silent Danger

Allergy season hits hard, and many moms reach for diphenhydramine (Benadryl) because it’s cheap and works fast. But here’s what you might not know: it crosses into breast milk easily, with milk-to-plasma ratios as high as 1.0. Studies show about 1.6% of infants exposed to diphenhydramine become noticeably drowsy. That doesn’t sound like much, but in a 6-week-old baby who’s already sleeping 16-18 hours a day, extra sleepiness can mean missed feeds. And missed feeds mean low weight gain, dehydration, and even hospital visits. One mom on Reddit shared that after taking one Benadryl, her 6-week-old became so sleepy she couldn’t wake him to nurse. The ER confirmed it was likely the medication. That’s not rare. The Breastfeeding Forum has documented 147 cases of infant drowsiness from first-gen antihistamines, with 37% happening after just one dose. These aren’t isolated stories-they’re warning signs.

The Safer Alternatives: Second-Generation Antihistamines

You don’t have to suffer through allergies just to keep your baby safe. The good news? There are much better options. Cetirizine (Zyrtec), loratadine (Claritin), and fexofenadine (Allegra) are all classified as L1-the safest category for breastfeeding. They transfer minimally into breast milk: loratadine only at 0.04-0.05% of your dose. That’s less than a drop in a bucket. Studies show no significant sedation in infants, even with daily use. One mom on BabyCenter reported using Zyrtec every day for months while nursing her 3-month-old and noticed zero changes in his sleep or feeding habits. Experts from the Cleveland Clinic and the American Academy of Pediatrics all agree: these are the first-choice antihistamines for nursing mothers. They work just as well as the old-school ones, without the drowsiness risk. And unlike diphenhydramine, they don’t linger in your system. Cetirizine has a half-life of about 8 hours, so even if a tiny bit gets into milk, it’s gone before the next feed.

Decongestants and Nasal Sprays: The Hidden Milk Supply Trap

If your nose is stuffed up, you might think pseudoephedrine (Sudafed) is the answer. But here’s the catch: it doesn’t just clear your sinuses-it can shut down your milk supply. A 2003 study in the Journal of Human Lactation found that just one dose of pseudoephedrine reduced milk production by 24% within 24 hours. That’s not a small dip-it’s enough to derail breastfeeding for some moms. And while it doesn’t cause sedation in babies, losing your supply is its own kind of crisis. Nasal steroids like fluticasone (Flonase) and budesonide (Rhinocort) are far better choices. They’re applied directly to your nose, so almost none of the drug enters your bloodstream. Less than 0.1% of the dose gets absorbed, making them safe and effective for allergic rhinitis during breastfeeding. The American Academy of Family Physicians recommends them as first-line treatment. And if you want to avoid meds entirely? Saline nasal sprays and humidifiers work surprisingly well for congestion without any risk.

Timing and Dosing: How to Minimize Risk

If you absolutely need to take a medication that carries some risk-like a first-gen antihistamine-you can reduce exposure by timing it right. The InfantRisk Center recommends taking the dose right after you nurse, then waiting 3-4 hours before the next feeding. That’s because most sedating drugs peak in breast milk 1-2 hours after you take them and clear out over the next few hours. Waiting 3-4 hours cuts infant exposure by more than half. Also, always use the lowest dose possible. One pill is enough. Taking two won’t make your allergies better-it just increases the chance your baby will feel the effects. And never take these meds daily unless you’ve talked to your doctor. Short-term use is fine. Long-term use? That’s when risks pile up.

What to Watch For in Your Baby

Even if you take the safest meds, keep an eye on your baby. Signs of medication-related sedation include: excessive sleepiness, difficulty waking for feeds, fewer wet diapers, shallow or irregular breathing, and poor latch or sucking. Newborns under two months are most at risk because their livers can’t break down drugs like older babies can. If you notice any of these signs after taking a new medication, stop the drug and contact your pediatrician. Don’t wait. A sleepy baby who won’t feed can quickly become dehydrated or develop jaundice. Trust your gut-if something feels off, it probably is.

What Experts Say About Codeine and Other High-Risk Drugs

Codeine is no longer recommended for breastfeeding mothers by the Academy of Breastfeeding Medicine or the American Academy of Pediatrics. Dr. Thomas Hale, author of the go-to reference book Medications and Mothers’ Milk, says the risk of respiratory depression in infants far outweighs any benefit. The Breastfeeding Network is even clearer: they say codeine should not be taken at all while breastfeeding. There have been documented cases of infant deaths linked to codeine use-even when moms took the exact dose prescribed. And it’s not just codeine. Hydroxyzine and chlorpheniramine are also flagged as potentially dangerous. The LactMed database, updated weekly by the NIH, now lists 17 cough and allergy medications with specific sedation warnings. That’s up from just 9 in 2018. The message is clear: the medical community is getting better at identifying these risks, and the guidelines are tightening.

What to Do If You’ve Already Taken a Risky Med

If you took diphenhydramine or codeine without knowing the risks, don’t panic. One dose rarely causes serious harm. But if your baby shows signs of sedation, call your pediatrician. If you’re worried about your milk supply after taking pseudoephedrine, pump and dump only if you’re experiencing significant discomfort. Otherwise, keep nursing-pumping and discarding won’t help your supply recover faster. In fact, it might make things worse by signaling your body to produce less. Instead, nurse frequently, stay hydrated, and consider using a breast pump to stimulate production if your baby isn’t feeding well. Most moms bounce back within a day or two.

Future Tools: Apps and Genetic Testing

The future of breastfeeding medication safety is getting smarter. New apps like LactaMap now pull real-time data from LactMed and give personalized risk assessments based on your baby’s age, health, and the specific drug you’re taking. And in the next few years, genetic testing for ultra-rapid metabolizers may become standard before prescribing codeine or similar drugs. A 2023 study showed these tests are 92% accurate at predicting who’s at risk. While it’s not routine yet, it’s coming. For now, the best tool you have is knowledge. Know what you’re taking. Know how it affects your baby. And don’t be afraid to ask your doctor or lactation consultant for alternatives.

Bottom Line: What to Take and What to Avoid

• Safe choices: Dextromethorphan (cough), cetirizine (Zyrtec), loratadine (Claritin), fexofenadine (Allegra), fluticasone (Flonase), budesonide (Rhinocort), ibuprofen
• Avoid: Codeine, hydroxyzine, chlorpheniramine, diphenhydramine (Benadryl), pseudoephedrine (Sudafed)
• Use with caution: Any sedating antihistamine-even if it’s "over-the-counter"-if you’re nursing a newborn

There’s no shame in needing help with allergies or a cough. But there’s huge value in choosing the right help. Your baby’s safety doesn’t mean you have to suffer. With the right meds, timing, and a little planning, you can manage your symptoms and keep breastfeeding strong.