Inflammation of breast tissue. Mastitis is usually caused by bacterial infection and sometimes by hormonal changes.
Mastitis usually occurs when bacteria enter the nipple during breast-feeding. It can also be caused by changes in levels of sex hormones in the body –for example, at the onset of puberty.
The condition causes pain, tenderness, and swelling in one or both breasts. Bacterial mastitis during breast-feeding also causes redness and engorgement and may result in a breast abscess.
Mastitis due to infection is treated with antibiotic drugs and analgesic drugs, and by expressing milk to relieve engorgement. Mastitis caused by hormonal changes usually clears up in a few weeks without treatment.