Mastitis, Clogged Ducts and Sore Nipples: What ANR Couples Need to Know

A hard lump. A tender spot. Breasts that feel like they've been filled with cement. If you're nursing or pumping regularly, at some point you may encounter a clogged duct or mastitis. Here's what's happening, how to tell the difference, and what to actually do about it.

Clogged Ducts: What They Are and Why They Happen

A clogged duct (also called a plugged duct) happens when milk isn't draining properly from part of the breast. Milk backs up behind the blockage, and the result is a firm, tender lump — sometimes pea-sized, sometimes larger — that doesn't go away between sessions.

You'll usually feel it before you see it. The lump is often tender to the touch, and the skin over it may look slightly red. The affected area might feel harder than the rest of the breast. Occasionally there's a noticeable decrease in milk flow from that side.

Common causes include:

Infrequent or missed nursing or pumping sessions
A poor latch that doesn't fully empty the breast
Wrong pump flange size, leaving some ducts consistently undrained
Sleeping on your stomach (sustained pressure on the breast)
A bra or clothing that's too tight
Fatigue, dehydration, or stress — all of which can affect milk flow

How to Clear a Clogged Duct

The goal is to get the milk moving. Most clogged ducts resolve within 24–48 hours with consistent attention.

Nurse or pump frequently on the affected side. This is the most important thing. More frequent emptying keeps milk moving and prevents the blockage from worsening. Don't skip sessions on the affected side because it's uncomfortable — that will make things worse.

Apply warmth before sessions. A warm compress, a warm shower, or a warm flannel held against the lump for a few minutes before nursing or pumping helps the duct relax and milk flow more easily.

Massage the lump. Gentle but firm massage, working from behind the lump toward the nipple, can help break up the blockage. Do this during nursing or pumping when milk is already moving. Some women find doing this in a warm shower helps.

Vary your position. If you always nurse or pump in the same position, some ducts may consistently drain better than others. Changing position — especially positioning so your partner's chin or the pump points toward the lump — can help drain the blocked area.

Stay hydrated and rest. Dehydration and fatigue both affect milk flow. If you're run down, your body will struggle to clear the blockage.

Lecithin. Sunflower or soy lecithin is an emulsifier that some women find helpful for reducing milk "stickiness" and preventing recurring blockages. It's generally considered safe and is commonly used in the breastfeeding community, though the evidence base is mostly anecdotal. If you get clogged ducts frequently, it may be worth trying.

When a Clogged Duct Becomes Mastitis

Mastitis is inflammation of the breast tissue — sometimes with infection, sometimes without. It can develop from an unresolved clogged duct, or it can come on without an obvious preceding blockage.

The key difference from a simple clogged duct is how you feel.

Signs of mastitis:

A tender, swollen, warm area of the breast — often with redness or a wedge-shaped red patch on the skin
Flu-like symptoms: fever (usually 38.5°C / 101°F or higher), chills, body aches, fatigue
Feeling genuinely unwell — not just uncomfortable, but sick

If you have a hard lump and feel fine otherwise, it's probably a clogged duct. If you have breast symptoms and feel like you have the flu, treat it as mastitis.

Treating Mastitis

Keep nursing or pumping. This is counterintuitive when you're in pain, but it's important. Stopping will make things worse — milk backing up provides more opportunity for bacterial growth. Continued drainage is part of the treatment.

Rest. Mastitis is your body under attack. Treat yourself as sick, because you are. Rest as much as you possibly can.

Apply warmth before sessions, cold between them. Warmth before nursing helps with let-down and drainage. Cold compresses between sessions can reduce inflammation and pain.

Pain relief. Ibuprofen (if you can take it) is particularly useful for mastitis because it's both a painkiller and an anti-inflammatory. Follow dosing instructions.

See a healthcare provider promptly. Non-infectious mastitis can sometimes resolve without antibiotics, but infected mastitis requires treatment. If your symptoms include fever, if you're feeling very unwell, or if things aren't improving within 12–24 hours of starting home treatment — see a doctor. Mastitis that isn't treated properly can progress to a breast abscess, which is significantly more serious.

Nipple Blebs

Sometimes a clogged duct is caused by a milk blister (bleb) — a small white or yellow spot on the nipple that blocks a duct opening. They look like a tiny pimple on or near the nipple tip.

Soaking in warm water and then nursing or pumping can sometimes clear them. Some women find gently rubbing with a warm flannel helps. If a bleb persists and is causing recurring blockages, a healthcare provider can open it — don't try to do this aggressively at home.

Prevention

Stay consistent with your nursing and pumping schedule — don't let too long pass between sessions
Make sure your latch is good and your pump flanges are the right size
Avoid sleeping on your stomach or anything that puts sustained pressure on the breast
Stay hydrated
Address any latch issues promptly rather than pushing through pain

Most clogged ducts and mastitis episodes resolve fully and don't cause lasting problems. The key is catching them early and acting quickly — don't wait to see if it resolves on its own if you're feeling unwell.