Mastitis

Mastitis occurs when bacteria — most often Staphylococcus aureus — enter breast tissue, typically through a cracked or sore nipple during breastfeeding. The body's immune response to the infection causes the characteristic redness, warmth, swelling, and pain. Women with mastitis often feel unwell in a broader sense, with fatigue, body aches, and a fever over 101°F (38.3°C).

Breastfeeding-related mastitis is the most common form, but mastitis can also occur in women who are not nursing — particularly those who have recently weaned, experienced breast trauma, or have a weakened immune system. In rare cases, mastitis can progress to a breast abscess, a painful pocket of pus that may require drainage in addition to antibiotics.

The good news is that mastitis responds well to treatment. Antibiotics are effective, and most women feel significantly better within a day or two of starting them. Continuing to breastfeed or pump during mastitis is generally recommended, as emptying the breast helps clear the infection. Applying warm compresses and resting can also ease discomfort. Mastitis is not cancer, and it does not increase your cancer risk — though any breast lump that does not resolve with treatment should be evaluated further.

Mastitis can feel alarming when it strikes, especially for new mothers who may be unsure whether breast pain and fever are normal parts of breastfeeding. Knowing the signs — redness, warmth, and that distinctive flu-like feeling — helps you seek treatment early before the infection has a chance to worsen into an abscess.

One of the most important things to know is that you do not need to stop breastfeeding with mastitis. In fact, continuing to nurse or pump is usually part of the treatment. If symptoms do not improve within a few days of starting antibiotics, or if you notice a new lump that persists after the infection clears, let your doctor know so they can investigate further.