Mastitis

Mastitis is a condition that causes a woman's breast tissue to become painful and inflamed. Mastitis is most common in breastfeeding women, although women who aren't breastfeeding can develop it. About 1 in 10 breastfeeding women are affected by mastitis. In these cases, it usually develops in the first three months after giving birth.

Doctors often refer to it as lactation mastitis or puerperal mastitis. Mastitis usually affects one breast. As well as the breast being painful and swollen, some women may also experience flu-like symptoms such as a high temperature (fever), aches and chills.

Schematic diagram showing mastitis and breast abscess

You should visit your physician immediately if you think you might have mastitis. They should be able to diagnose it. If you're breastfeeding, they may ask you to demonstrate your technique. 

Try not to feel as if you are being tested or blamed, breastfeeding correctly can take time and practice. In non-breastfeeding women, your doctor will want to rule out other conditions.

What causes mastitis?
Mastitis can be caused by an infection or milk remaining in the milk tissue (milk stasis). Milk stasis can occur for a number of reasons, such as your baby not being properly attached to your breast during feeding.

Infectious mastitis may develop if bacteria gets into your milk ducts. This can be because your milk ducts are blocked or, in non-breastfeeding women, because of a cracked or sore nipple, or nipple piercing. Left untreated, non-infectious mastitis can develop into infectious mastitis. This may be due to bacteria infecting milk that remains in the breast tissue.

During breastfeeding, the milk ducts may get blocked, leading to mastitis


Treating mastitis 
Most cases of mastitis can be effectively treated. Rest, drinking plenty of fluids and, if necessary, adjusting your breastfeeding technique, may be all that is needed. When breastfeeding, make sure your baby is properly attached to your breast and that your nipple is positioned deep inside your baby's mouth.

Your breast should feel softer and lighter after the feed but there may still be a small amount of milk left over. In some cases it may be necessary to:
  • feed more frequently
  • express any remaining milk after a feed
  • express milk between feeds.

All cases of infectious mastitis will need to be treated with antibiotics to bring the infection under control.

During mastitis, the affected breast is red, hot, swollen and painful

Can I still breastfeed with mastitis?

Although the symptoms of mastitis may discourage you from breastfeeding, it is important that you try to continue. Regular breastfeeding will help:

  • remove any blocked breast milk from your breast
  • resolve symptoms of mastitis more quickly
  • prevent mastitis from becoming more serious.


The milk from the affected breast may be a little saltier than normal, but it is safe for your baby to drink. Any bacteria present in the milk will be harmlessly absorbed by the baby's digestive system and will not cause any problems. If you have severe or persistent mastitis, your doctor may decide to take a small sample of your breast milk for testing.

Complications of mastitis

Mastitis should be promptly treated to prevent more serious complications developing , such as a breast abscess (a painful collection of pus).