Decongestants, Illness, and Milk Supply: What Winter Medications Really Do

Educational only — always speak with your healthcare provider before starting any medication.

Winter is the season of sniffles, congestion, and those “please don’t let this turn into something worse” moments. For breastfeeding parents, getting sick brings a new layer of worry:

“Will cold medicine hurt my supply?”“Is it even safe to breastfeed while I’m sick?”“What can I take without affecting my baby?”

It can feel like every choice has consequences — especially when you're exhausted, congested, and just want to breathe through your nose again. The good news? Most winter illnesses do not require you to stop breastfeeding, and many medications are compatible with lactation. But there are a few important exceptions worth knowing about.

Let’s break down what the research actually tells us.

Breastfeeding While Sick: Why It’s Usually The Best Thing You Can Do

When you catch a cold or virus, your baby has almost certainly been exposed before you even feel symptoms. Continuing to breastfeed gives your baby something incredibly valuable: illness-specific antibodies carried directly through your milk. These antibodies begin forming within hours of exposure and help protect your baby from the illness you’re fighting.¹

Not only is breastfeeding safe during most respiratory illnesses — it’s actually beneficial.

Stopping suddenly can lead to:

• Engorgement

• Plugged ducts

• Higher risk of mastitis

• A temporary drop in milk supply

So rest, hydrate, and keep breastfeeding if you feel up to it.

Where Things Get Tricky: Decongestants and Milk Supply

Here’s the part almost every breastfeeding parent has heard rumors about — and yes, there’s truth to it.

Pseudoephedrine (Sudafed)

This is the one medication with strong evidence showing it can reduce milk supply. In a well-known study, a single standard dose of pseudoephedrine decreased milk production by about 24%.²

This doesn’t mean everyone will experience a drastic drop, but many parents do notice:

• Softer breasts

• Lower pump output

• A fussier baby due to slower flow

And supply may not rebound immediately after you stop taking it.

If your supply is still regulating, has dipped in the past, or feels sensitive to changes, pseudoephedrine is usually something to avoid unless recommended by your provider.

Phenylephrine (the “PE” formulas)

Phenylephrine (Sudafed PE) doesn’t have the same research showing a clear drop in supply.³ It’s not as effective as pseudoephedrine for congestion relief, but it’s less likely to interfere with milk production.

Still — evidence is limited, so always check with a healthcare professional.

What About Antihistamines? Do They Reduce Supply?

This is a common concern, especially with older drowsy antihistamines like diphenhydramine (Benadryl).

Here’s what the research shows:

• Sedating antihistamines may have a mild prolactin-suppressing effect,

• But real-world supply drops are uncommon, and usually only when combined with dehydration or infrequent feeding.⁴

• Newer antihistamines (loratadine, cetirizine) are generally considered compatible with breastfeeding and not linked to reduced supply.⁵

So antihistamines are usually not the problem — dehydration and skipped feedings during illness often are.

Illness Itself Can Temporarily Lower Supply

Even without medication, you may notice:

• Lower appetite

• Less frequent feeding or pumping

• Stress or discomfort that affects let-down

• Mild dehydration

These changes can cause supply to dip for a few days, but it almost always rebounds once you’re feeling better, feeding regularly, and staying hydrated.

Safer Symptom Relief Options to Discuss With Your Provider

Many breastfeeding parents manage congestion with:

• Saline nasal spray

• Nasal rinses

• Humidifiers

• Warm steam

• Honey (for adults only)

• Ibuprofen or acetaminophen

• Hydration and rest

None of these are known to impact supply, and they can take the edge off while your body heals.

The Bottom Line

• Breastfeeding while sick is safe — and protective — for your baby.

• Pseudoephedrine is the main medication proven to reduce milk supply.

• Phenylephrine is less likely to cause issues, but evidence is limited.

• Antihistamines are generally safe when used appropriately.

• Illness itself can temporarily lower supply, but it usually rebounds quickly.

• Always talk to your doctor or pharmacist before starting any medication while breastfeeding.

If you’re unsure about your options, an IBCLC and your healthcare team can work together to help you choose the safest, most effective symptom relief — without sacrificing your feeding goals.

References (AMA Style)

1. Goldman AS. The immune system in human milk and the developing infant. Breastfeed Med. 2007;2(4):195–204.

2. Aljazaf K, Hale TW, Ilett KF, et al. Pseudoephedrine: effects on milk production in women and estimation of infant exposure via breastmilk. Br J Clin Pharmacol. 2003;56(1):18–24.

3. Ito S, Blajchman A, Stephenson M, et al. Prospective follow-up of adverse reactions in breastfed infants exposed to maternal medication. Am J Obstet Gynecol. 1993;168(5):1393–1399.

4. Berle JØ, Steen VM, Aamo TO, Breilid H, Zahlsen K, Spigset O. Breastfeeding during maternal antihistamine therapy. J Hum Lact. 2014;30(1):5–10.

5. Hale TW. Medications & Mothers’ Milk. 2023.