Mastitis causes a woman's breast tissue to become painful and inflamed. It's most common in breastfeeding women, usually within the first six weeks after giving birth. Up to a third of women breastfeeding may develop mastitis, compared with 5-9 per cent of women who have not recently been pregnant.

Symptoms of mastitis 

Mastitis usually only affects one breast, and symptoms often develop quickly.

If mastitis is caused by breastfeeding, doctors may refer to it as lactation mastitis or puerperal mastitis. Women who have not been pregnant and lactating (producing breast milk) will have a type called periductal mastitis.

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 as soon as possible. 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. This can be as a result of damage to the nipple, such as a cracked or sore nipple, or a nipple piercing.

However, it can also occur if you have a condition that affects your body’s immune system or ability to fight infection.

Diagnosing mastitis 

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

If you are breastfeeding, your GP will talk to you about how you are getting on and can help if you have any questions about breastfeeding.

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 find out if you have a bacterial infection and allow your GP to prescribe an effective antibiotic.

If you have mastitis and aren't breastfeeding, your GP may refer you to hospital for a specialist examination and a breast scan to rule out other conditions. This is usual 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. It can also help improve your symptoms.

It may also help to:

  • feed more often than usual
  • express any remaining milk after a feed
  • 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. This is to bring the infection under control.

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 only for around six months, if possible
  • encourage your baby to feed often, particularly when your breasts feel overfull
  • make sure 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

Research suggests smoking increases the risk of periductal mastitis - a type that affects women who have not been pregnant and lactating (producing breast milk).

There is free specialist advice available to help you quit smoking. Stop smoking support services, through GP practices and community pharmacies, are available across Northern Ireland.

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.

The information on this page has been adapted from original content from the NHS website.

For further information see terms and conditions.

This page was reviewed November 2017

This page is due for review August 2019

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