Mastitis: Recognise It Early and Treat It Right

It came on in about four hours, the first time. Fine at lunch, and by mid-afternoon I was shivering under a blanket in thirty-degree heat, a hard, hot, red patch on the side of my left breast, feeling like I had the flu out of nowhere. I remember thinking, genuinely, that I’d caught some kind of virus, because nothing about how it felt seemed connected to breastfeeding. It was entirely connected to breastfeeding. That’s mastitis, and it’s far more common, and far more manageable, than how frightening it feels in the first hour of it tells you.

What’s actually happening

Mastitis is inflammation of breast tissue, most often triggered by a blocked milk duct that hasn’t cleared where milk builds up behind the blockage, the surrounding tissue becomes inflamed, and your body responds the way it would to any inflammation: heat, redness, pain, and often the flu-like symptoms that make it feel like something entirely separate from your breast is wrong. It can happen with or without an infection. If bacteria enter, usually through a cracked nipple, it can become infected, which is when antibiotics come into the picture. But the inflammation itself, in its early stages, is not automatically an infection.

How to recognise it

A firm, hot, red, and painful area on the breast, usually confined to one section rather than the whole breast. It can appear anywhere but is common on the outer side or underside, where milk pools most easily if a feed doesn’t fully drain that area. Alongside the local symptoms: fever, chills, body aches, and a general flu-like exhaustion that can genuinely feel disconnected from your breast until you notice the two are happening together.

It tends to come on fast, over hours rather than days, which is part of what makes it so disorienting the first time.

What to do in the first 24 hours

Keep feeding, including from the affected breast, and if anything, feed more frequently from that side, not less. This is the part that goes against instinct as the breast hurts, and the instinct is to protect it by not touching it. But mastitis clears fastest when the blockage behind it is cleared, and the most effective way to clear it is continued, effective milk removal. Stopping feeding from that side is one of the most common reasons a mild case progresses to something more serious.

Positioning matters here: try angling your baby’s chin toward the blocked area during a feed if you can identify roughly where it is, since babies drain most effectively from wherever their chin points.

Warmth before feeds (a warm compress or a warm shower) helps encourage let-down and loosen the blockage. Cold compress after feeds reduces the inflammation and eases the pain. Gentle massage toward the nipple during the feed, working from behind the lump forward, can help, though firm or aggressive massage isn’t necessary and can sometimes make tissue more inflamed rather than less.

Rest, as much as you can manage. Your body is fighting inflammation on top of everything else it’s doing.

When to call a doctor

If symptoms haven’t meaningfully improved within 24 hours of the steps above, or if you develop a fever above 38.5°C, contact your doctor. This isn’t a “wait and see how it goes for a few more days” situation, mastitis that progresses can develop into a breast abscess, which is a considerably more serious complication requiring drainage, sometimes surgical. It’s far better to get antibiotics started a day earlier than needed than a day later than needed.

Antibiotics, if prescribed, are safe to continue breastfeeding through as your doctor will choose one compatible with lactation. Continuing to feed while on antibiotics is not only safe, it remains the most effective way to clear the remaining blockage.

What increases the risk

Missed or delayed feeds, a shallow latch that isn’t fully draining the breast, sudden changes in feeding pattern (a baby sleeping through the night earlier than usual, for example, without you adjusting), pressure on the breast from a tight bra or sleeping position, and general exhaustion or a lowered immune response, which is part of why mastitis often shows up in weeks when everything else is already a lot.

The reassurance worth ending on

Mastitis, treated properly and early, typically resolves within a few days. It is not a sign you’re doing anything wrong, and it doesn’t mean you need to stop breastfeeding, for almost everyone, it means the opposite: keep feeding, treat it properly, and it passes.

Disclaimer: This article is for informational purposes only and does not replace medical advice. If you suspect mastitis, particularly with fever, contact your doctor promptly.