Acute mastitis is an acute purulent infection of the breast, which is an inflammation of the connective tissue in and around the ducts of the breast. It can be divided into acute mastitis during lactation and non-lactation. It is more common during lactation, especially in first-time mothers. Acute mastitis during lactation often starts with systemic symptoms of toxicity, such as high fever and chills, with a temperature of up to 40°C. Local symptoms can vary depending on the stage of the disease and the time of day. Local symptoms may vary depending on the stage of the disease and the depth of the lesion. If the lesion is deep, the local manifestations are mostly pain and pressure, while if the lesion is shallow, the typical manifestations of purulent inflammatory manifestations of inflammation can occur. Initially, the main manifestations are an increase in the volume of the affected breast, a limited lump and pressure pain, which can gradually subside if treated effectively in time. If further developed, there can be edema and redness of the skin and increased skin temperature. The local mass is stiff, with significant pressure pain, and may develop throbbing pain. If it continues to develop, the hard mass will gradually become soft in a short period of time, indicating that an abscess has formed. The abscess may break down on its own or drain through the nipple. The axillary lymph nodes on the affected side are often enlarged and painful to pressure. In non-lactating mastitis, the systemic symptoms are milder and the local symptoms are predominant, with pain in the affected breast, redness of the surface skin, local stiffness, and further development of abscesses, with nipple indentation at the site of infection if it occurs next to the areola. In summary, it is important to prevent the occurrence of mastitis during breastfeeding, to develop the habit of breastfeeding regularly, and to keep the nipples clean.