Mastitis

Also called Breast inflammation

Mastitis is when the breast becomes swollen, hot and painful. It is most common in people who are breastfeeding, often in the first 3 months, when milk builds up in the breast. It can also happen when not breastfeeding, for example due to infection, smoking or nipple piercings.

Last updated Nov 9, 2026

What it is

Continuing to breastfeed or express milk, resting, pain relief and cold compresses usually help. Antibiotics are needed if it does not improve or there is infection.

Untreated, it can sometimes lead to a breast abscess.

Common signs

  • A swollen, hot and painful area of the breast
  • Redness, which may be harder to see on darker skin
  • A wedge-shaped lump
  • Flu-like symptoms such as fever and aches

How it is usually diagnosed

  • Examination of the breast
  • Milk sample or ultrasound, sometimes

Records worth keeping

Keeping these together makes each appointment easier, especially when you see a new doctor:

  • Notes on episodes and treatment
  • Ultrasound reports, if done

Questions to ask your doctor

  • Should I keep breastfeeding?
  • Do I need antibiotics?
  • How can I prevent it coming back?

When to get help right away

Call 112 or go to the nearest emergency department if you have:

  • High fever, feeling very unwell, fast heartbeat or confusion: get urgent medical help, it may be sepsis

This page is general information. It is not a diagnosis and does not replace a doctor who knows your history. Medfold keeps your records organised; it does not interpret them.

Sources