What can happen if mastitis is untreated?

Mastitis may begin with a painful, warm, red, or swollen area. If bacterial infection is involved, inflammation can intensify and a pocket of pus may form. An abscess often feels like a distinct lump and may cause ongoing tenderness or fever. Symptoms can also have a non-infectious cause, so worsening symptoms should not be self-diagnosed. A clinician can check whether the breast is healing, whether medicine is needed, and whether another breast condition needs investigation.

Contact a healthcare professional when symptoms persist, spread, or interfere with daily activity. Until you are assessed, rest, drink fluids, use a suitable pain reliever if you can take one, and avoid pressing or repeatedly checking the sore area. Take prescribed medicine exactly as directed and arrange follow-up if improvement does not start. For background on the symptom, see [Breast Pain](/symptoms/breast-pain/).

Seek same-day care for fever, chills, spreading redness, pus, a growing lump, or pain that is becoming severe. Urgent help is needed for confusion, fainting, breathing difficulty, or severe weakness. If a course of treatment ends but the lump or redness remains, arrange another examination rather than waiting for it to resolve on its own.

Could an abscess be developing? Do I need imaging or drainage? What improvement should I expect after treatment? When should I have the breast checked again?