Breastfeeding While Sick: Why Your Milk Keeps Working Through Cold and Flu Season
It usually starts with a scratchy throat at 3 a.m. and a baby who wants to nurse. Then the worry kicks in: should I keep breastfeeding, or am I about to pass this to my baby through my milk? Every fall, this is one of the questions I hear most from families across NYC, and the answer surprises a lot of people.
The Myth: "Stop Nursing So the Baby Doesn't Catch It"
This advice gets passed along by loving grandparents, friends, and sometimes even well-meaning professionals. It sounds protective. But for common illnesses like colds and the flu, it gets the science backwards.
Respiratory viruses spread through droplets when we cough, sneeze, or talk, and through hands that touch our face and then touch the baby. The CDC states plainly that flu is not transmitted through breast milk, and it recommends that mothers with the flu keep providing their milk while taking precautions. Flu can also spread before you even feel sick, so by the time symptoms show up, your baby has often already been around the virus.
What Your Milk Is Doing While You Feel Awful
Here is the part I love teaching. When you are exposed to a germ, your immune system starts making antibodies targeted to that exact germ. Those antibodies, especially a type called secretory IgA, travel into your milk and coat the lining of your baby's throat and gut. You are essentially sharing a custom immune response that your baby is too young to build on their own.
The CDC notes that breast milk contains antibodies and other immune factors that can help protect infants from the flu, and that breastfed infants are less vulnerable to infections, including severe lower respiratory illness. Research also suggests milk responds to illness in real time. In a small study by Riskin and colleagues (2012), the immune cells in mothers' milk rose when their nursing babies were actively sick, then returned to baseline after recovery.
Protect Your Baby From Droplets, Not From Your Milk
The goal is to keep the germs on your hands and in your breath away from your baby while you keep the milk coming. A few habits make a real difference:
- Wash your hands with soap and water for at least 20 seconds before touching your baby, your pump parts, or bottles.
- Wear a mask while feeding or holding your baby close.
- Cough or sneeze into a tissue or your elbow, toss the tissue, and wash again.
- If you are too sick to nurse, pump on your usual schedule and let a healthy caregiver feed your expressed milk.
- Clean pump parts after every use, following the CDC's pump hygiene steps.
Keeping Your Supply Steady While You Recover
The CDC acknowledges that milk supply can dip for some parents while they are ill. Fever, less fluid, fewer feeds, and simple exhaustion all play a role. Some medications matter too. Pseudoephedrine, the decongestant in many cold products, is the one I flag most often. In a small study by Aljazaf and colleagues (2003), a single 60 mg dose reduced milk production by about 24 percent over the next 24 hours, and the LactMed database notes that repeated use may interfere with lactation.
The good news: in my practice, supply usually rebounds once a parent is well and milk removal is frequent again.
Medications, Vaccines, and When to Call Your Provider
Many common cold and flu remedies are compatible with breastfeeding, but "compatible" depends on the specific drug and dose. LactMed, a free database from the National Library of Medicine, is the resource I use daily. Your pharmacist can look things up there with you. If you are prescribed an antiviral for the flu, the CDC lists oseltamivir as the preferred option during breastfeeding because very little passes into milk.
On prevention, the CDC states that the flu vaccine is safe during breastfeeding and that parents who are vaccinated pass flu antibodies to their babies through milk. Babies under 6 months cannot get the flu vaccine themselves, which is why vaccinating everyone else in the household matters so much.
This post is general education, not a substitute for care from your own clinicians. Call your baby's pediatrician right away for a fever of 100.4°F or higher in a baby under 3 months, fewer wet diapers, labored breathing, or a baby who will not feed. Call your own provider for a high or lasting fever, or a breast that is red, hot, and painful, since missed feeds during illness can raise the risk of mastitis.
When Your Baby Is the One Who's Sick
The CDC also recommends that babies with the flu keep breastfeeding, since sick babies need fluids and your milk is the best option. Congestion can make feeding frustrating, though. Babies breathe through their noses while they nurse, so a stuffy nose can lead to short, fussy feeds or even a temporary refusal that looks like a nursing strike.
You Don't Have to Figure This Out Alone
If illness has thrown off your supply, your baby is refusing the breast, or you just want a plan before cold season peaks, I can help. I see families in their homes across NYC, Westchester, and Western Connecticut, and I offer virtual visits too, which are perfect when someone in the house is contagious. Many plans cover lactation care, so check my insurance page to see what applies to you.
Book a VisitI'm an International Board Certified Lactation Consultant with a Doctor of Public Health, and I've spent years helping NYC families feed their babies with evidence, not guilt. Learn more about me here.
- Centers for Disease Control and Prevention. Influenza (Flu) and Breastfeeding. Updated September 23, 2025.
- Riskin A, et al. Changes in immunomodulatory constituents of human milk in response to active infection in the nursing infant. Pediatric Research, 2012.
- Aljazaf K, et al. Pseudoephedrine: effects on milk production in women and estimation of infant exposure via breastmilk. British Journal of Clinical Pharmacology, 2003.
- Drugs and Lactation Database (LactMed). National Library of Medicine.