Blocked Ducts: What They Are, Why They Happen, and How to Help

During breastfeeding, milk travels through a network of small tubes — the milk ducts — from the milk-producing glands to the nipple. When milk is not flowing easily through part of the breast, the surrounding tissue can become inflamed and swollen, and this is what we now understand as a blocked duct.

You will notice I said "inflamed and swollen" rather than "blocked by a plug." Current thinking has moved away from the old idea of a lump of thickened milk physically blocking a tube. More recent evidence suggests it is the tissue itself swelling up that causes the narrowing of the ducts. NCT This is an important shift — it changes how we think about treatment too, which I will come to in a moment.

What does it feel like?

The most common sign is a localised tender lump or firm area in one breast, which may feel warm, look red or darker depending on your skin tone, and feel sore to touch. Your baby may fuss at that breast during a feed because the milk is flowing more slowly than usual. A blocked duct tends to come on gradually rather than suddenly.

Why do blocked ducts happen?

Anything that hinders milk flowing easily from all areas of the breast can cause this kind of inflammation. Mother Food Common reasons include:

• Gaps between feeds — whether due to your baby sleeping longer, teething, going back to work, nipple pain, or a change in feeding patterns

• Your baby not latching deeply or draining the breast well

• Pressure on the breast tissue from a tight bra, underwired bra, a bag strap, seatbelt, or sleeping position

• Oversupply of milk — particularly common in the early weeks — which increases the risk if not well managed Grokipedia

• Stress, fatigue, anaemia, and a weakened immune system Mayo Clinic Health System

• Abrupt changes to feeding patterns, such as sudden weaning or starting solids

A note on the research

There is now a broader understanding of blocked ducts and mastitis as part of the same continuum of breast inflammation, rather than separate conditions. What were previously thought of as separate problems — blocked ducts, mastitis, milk blebs, and abscesses — are now suggested to be stages in the same inflammatory process, which is the body's response to a threat. LLLI The Academy of Breastfeeding Medicine updated their guidelines on this in 2022 (ABM Protocol #36, available at: https://pubmed.ncbi.nlm.nih.gov/35576513/).

What to do

The goal is to support milk flow and reduce inflammation — not to force milk out aggressively.

Feed your baby responsively. This is still the most important thing. Feed as often as your baby needs — but it is not recommended to try to "empty" the breast, as overfeeding or pumping to empty can perpetuate a cycle of oversupply and worsen inflammation. Lllasia

Use cold, not heat. This may surprise you if you have seen older advice. Updated guidance now recommends ice or a cold compress rather than heat, because cold reduces the blood flow and cuts down on swelling, whereas heat increases blood flow and may worsen symptoms. Motherly That said, some women find warmth soothing — a brief warm shower before a feed may help milk flow, just do not apply prolonged heat to an inflamed area.

Take ibuprofen if you can. Ibuprofen is more useful than paracetamol for this kind of breast inflammation because it reduces swelling as well as pain, and is safe to take while breastfeeding. Laleche Always check with your pharmacist if you are on other medication.

Gentle lymphatic massage. Rather than vigorous massage over the lump (which is no longer recommended), gentle lymphatic drainage using a very light touch in the armpit area and upper chest can help to move fluid away from the ducts. LLLI There are good demonstration videos online via the Institute for the Advancement of Breastfeeding and Lactation Education (IABLE).

Check positioning and latch. Make sure your baby has a good, deep latch and is feeding effectively. This is one of the most important things you can do to prevent and resolve blocked ducts.

Try different feeding positions. Dangle feeding or varying position can help milk drain from different areas of the breast.

Lecithin. The use of lecithin may help milk move through the ducts more easily. It is thought to work by making the milk less sticky rather than by acting as a true emulsifier. Lllasia It is sunflower or soy lecithin that is most commonly used. The evidence for this supplement is not strong LLLI, but many women do find it helpful, particularly for recurrent blocked ducts. It is worth noting that choline — a nutrient found naturally in eggs, fish, broccoli, and cauliflower — is thought to be the active component, and choline supplements are also available.

Probiotics. Newer research has found that probiotics may help prevent and reduce the incidence of mastitis and are considered safe during breastfeeding. The strains that have been studied are Lactobacillus fermentum and Lactobacillus salivarius. Mayo Clinic Health System However, more research is still needed in this area LLLI and this should not replace the core management steps above.

When to seek help

If your symptoms have not improved within 24–48 hours, or if you develop a fever, flu-like symptoms, or feel significantly unwell, please contact your GP. These can be signs that inflammation has progressed to bacterial mastitis, which may need antibiotic treatment. Do not delay seeking help if you are deteriorating — mastitis that is not treated can develop into an abscess.