Mastitis is a condition which causes a woman’s breast tissue to become painful and inflamed. It’s most common in breastfeeding women, usually within the first three months after giving birth.

If mastitis is caused by breastfeeding, doctors may refer to it as lactation mastitis or puerperal mastitis. Non-breastfeeding women often have a type called periductal mastitis.

Symptoms of mastitis

Mastitis usually only affects one breast, and symptoms often develop quickly. Symptoms of mastitis can include:

  • a red, swollen area on your breast that may feel hot and painful to touch
  • breast lump or area of hardness on your breast
  • a burning pain in your breast that may be continuous or may only occur when you are breastfeeding
  • nipple discharge, which may be white or contain streaks of blood

You may also experience flu-like symptoms, such as aches, a high temperature (fever), chills and tiredness.

When to seek medical advice

Contact your GP as soon as possible if you think you might have mastitis. It may help to try some self-help measures before your appointment.

It’s important to see your GP promptly as mastitis could lead to a painful collection of pus (breast abscess), which may need to be drained surgically.

Causes of mastitis

In breastfeeding women, mastitis is often caused by a build-up of milk within the breast. This is known as milk stasis.

Milk stasis can occur for a number of reasons, including:

  • a baby not properly attaching to the breast during feeding
  • a baby having problems sucking
  • infrequent feeds or missing feeds

In some cases, this build-up of milk can also become infected with bacteria. This is known as infective mastitis.

In non-breastfeeding women, mastitis most often occurs when the breast becomes infected as a result of damage to the nipple, such as a cracked or sore nipple, or a nipple piercing.

Read more about the causes of mastitis.

Diagnosing mastitis

Your GP can often diagnose mastitis based on your symptoms and an examination of your breasts.

If you’re breastfeeding, they may ask you to show them how you breastfeed. Try not to feel as if you’re being tested or blamed – it can take time and practise to breastfeed correctly.

Your GP may request a small sample of your breast milk for testing if:

  • your symptoms are particularly severe
  • you’ve had recurrent episodes of mastitis
  • you’ve been given antibiotics and your condition hasn’t improved

This will help determine whether you have a bacterial infection and allow your GP to prescribe an effective antibiotic.

If you have mastitis and aren’t breastfeeding, your GP should refer you to hospital for a specialist examination and a breast scan to rule out other conditions, particularly if your symptoms haven’t improved after a few days of treatment.

Scans you may have include an ultrasound scan or a mammogram (X-ray of the breast).

Treating mastitis

Mastitis can usually be easily treated and most women make a full recovery very quickly.

Self-help measures are often helpful, such as:

  • getting plenty of rest and staying well hydrated
  • using over-the-counter painkillers, such as paracetamol or ibuprofen, to reduce any pain or fever
  • avoiding tight-fitting clothing – including bras – until your symptoms improve
  • if you’re breastfeeding, continuing to feed your baby and making sure they are properly attached to your breast

Breastfeeding your baby when you have mastitis, even if you have an infection, won’t harm your baby and can help improve your symptoms.

It may also help to feed more frequently than usual, express any remaining milk after a feed, and express milk between feeds.

For non-breastfeeding women with mastitis and breastfeeding women with a suspected infection, a course of antibiotic tablets will usually be prescribed to bring the infection under control.

Read more about treating mastitis.

Preventing mastitis

Although mastitis can usually be treated easily, the condition can recur if the underlying cause isn’t addressed.

If you’re breastfeeding, you can help reduce your risk of developing mastitis by taking steps to stop milk building up in your breasts, such as:

  • breastfeed exclusively for around six months, if possible
  • encourage your baby to feed frequently, particularly when your breasts feel overfull
  • ensure your baby is well attached to your breast during feeds – ask for advice if you’re unsure
  • let your baby finish their feeds – most babies release the breast when they’ve finished feeding; try not to take your baby off the breast unless they’re finished
  • avoid suddenly going longer between feeds – if possible, cut down gradually
  • avoid pressure on your breasts from tight clothing, including bras

Your GP, midwife or health visitor can advise about how to improve your breastfeeding technique. You can also call the National Breastfeeding Helpline on 0300 100 0212 for advice.