A blocked duct feels like a tender lump in the breast that doesn’t shift after a feed. Mastitis is that plus inflammation: the area goes red and hot, and you often feel unwell with it, flu-like and shivery.
Warmth has a narrow role here, and the advice has changed. Long soaks and aggressive massage used to be standard and are now discouraged, because they add swelling to tissue that’s already inflamed.
Where warmth helps
A short application of gentle warmth just before a feed can help the milk flow and make the let-down easier. That’s it. A few minutes, comfortably warm, not hot.
After the feed, cold is what settles things: a cold pack on the sore area for 10 to 15 minutes reduces the swelling and the pain. Many women find cold is the more useful of the two overall. On choosing between them generally, see hot or cold compress for swelling.
Why not more heat
Current thinking treats a blocked duct less as a plug to be forced out and more as swelling in the surrounding tissue squeezing the duct narrow. Prolonged heat widens blood vessels and increases that swelling, which can make the lump feel worse rather than better. It’s the same mechanism that rules heat out in the first days after an injury.
The same reasoning ended the advice to massage hard or use a vibrating device on the lump. Firm massage bruises inflamed breast tissue. If you touch the area at all, it should be light, in the direction of the armpit, and it should not hurt.
What actually helps
- Keep feeding normally. Milk moving is the main treatment, and it’s safe for the baby to feed from that side.
- Don’t over-pump to empty the breast. Extra pumping signals for more milk, which makes the problem larger.
- Cold after feeds for pain and swelling.
- Rest, fluids, and a well-fitting bra that isn’t compressing the area.
- Ask a pharmacist about an anti-inflammatory suitable while breastfeeding.
If you use a heat pad
- Lowest setting, cover on, a few minutes only, immediately before a feed. This is much shorter than an ordinary session.
- Never on cracked or broken nipple skin. Broken skin is on the list in who should not use a heating pad.
- Never while feeding, and never while you might doze off with the baby
- Stop if the area feels more swollen or more painful afterwards
Exhaustion is part of this picture, and a warm pad plus a newborn is exactly the situation where people fall asleep with it on. See is it safe to sleep with a heating pad on?
See a doctor if…
- You have a fever or feel increasingly unwell
- Symptoms aren’t improving within about 24 hours, or are getting worse
- The redness is spreading, or there’s a firm, very tender swelling that could be an abscess
- You see pus, or blood in the milk
- A lump remains after everything else has settled. Any breast lump that doesn’t resolve needs checking, breastfeeding or not.
Mastitis often needs antibiotics, and delaying raises the risk of an abscess. A lactation consultant is also worth seeing early, particularly if this keeps happening, because recurrent blockages usually trace back to positioning, attachment or supply rather than to anything you’re doing with heat.
Related: neck and back pain from carrying a newborn, sore thumbs and wrists from lifting a baby, heat after a C-section, and heat during pregnancy and after birth.
Clinically reviewed by: Nigel Chua (Hand Occupational Therapist) & Louise Yow (Physiotherapist). This article is general information, not a diagnosis. electricheatpad.com sells electric heat pads.
