Mastitis (breastfeeding)

Mastitis is a condition that causes the breast tissue to become painful and inflamed (red and swollen). As it usually occurs in women who are breastfeeding, it is often referred to as lactation mastitis or puerperal mastitis.

See the Health A-Z topic about Non-breastfeeding mastitis for more information about mastitis in women who are not breastfeeding.

Mastitis usually only affects one breast. Some women may also experience flu-like symptoms such as:

• high temperature (fever) of 38C (100.4F) or above
• chills
• aches

Types of mastitis

There are two main types of mastitis:

• non-infectious mastitis, which is usually caused by breast milk remaining within the breast tissue (milk stasis) as a result of a blocked milk duct or problems with breastfeeding
• infectious mastitis, which is usually caused by bacteria

Left untreated, non-infectious mastitis can develop into infectious mastitis. This may be due to bacteria infecting the milk that remains in the breast tissue.

How common is mastitis?

Around one in 10 women who are breastfeeding are affected by mastitis. Most women who get mastitis will develop it during the first three months after giving birth.

Continue breastfeeding

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

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

The milk from the affected breast can be a little saltier than normal, but it is safe for the baby to drink. Any bacteria that is present in the milk will be harmlessly absorbed by the baby's digestive system and cause no problems.

Outlook

Most cases of mastitis can be successfully treated using self-help measures, such as resting and drinking plenty of fluids and by adjusting the technique being used to breastfeed. It is important to ensure that the baby is properly attached to the nipple and that the breast is empty after the feed. In some cases it may be necessary to:

• feed more frequently
• express any remaining milk after a feed
• express milk between feeds

Expressing breast milk means that you encourage it to flow by hand or using a pump.

Infectious mastitis requires prompt treatment to prevent more serious complications developing in the breast, such as an abscess (a painful collection of pus). More serious cases of infectious mastitis will require antibiotics in order to bring the infection under control.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Ducts
The tubes that transport milk in the breast.

Antibiotics
Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi.

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

Symptoms of mastitis include:

• a red area on your breast that may feel hot and painful to touch
• the breast can then start to appear lumpy and red
• a burning pain in the breast that may be continuous or may only occur when you are breastfeeding
• your breast may also feel hard

Over half of women with mastitis may also experience flu-like symptoms such as:

• aches
• a high temperature (fever) of 38C (100.4F) or over
• shivering and chills
• feeling tired
• feeling generally unwell

When to seek medical advice

Always contact your GP or midwife if you think that you have mastitis.

Although mastitis is not usually serious, advice and prompt treatment may be required to prevent the condition getting worse. Seeing your GP or midwife will help to reassure you and ease any feelings of anxiety that you have.

Mastitis may have different causes depending on whether it is infectious or not. 

Non-infectious mastitis

It is thought that most cases of non-infectious mastitis are caused by milk stasis. Milk stasis occurs when the milk is not properly removed from your breast.

Milk stasis can be caused by:

• your baby not being properly attached to your breast during feeding, which may mean that not enough milk is removed or may cause pain in your nipple
• your baby having problems sucking, for example, because they have a tongue-tie (a piece of skin between the underside of their tongue and the floor of their mouth)
• your baby having infrequent feeds or missing feeds, for example, when they start to sleep through the night
• favouring one breast for breastfeeding, this can lead to milk stasis developing in the other breast
• pressure on your breast, for example, from tight-fitting clothing, an over-restrictive bra or sleeping on your front

Milk stasis can lead to blocked milk ducts in your breasts because the breast milk is not being properly and regularly expressed (encouraged to flow out of your breasts).

Experts are still unsure why breast milk can cause the breast tissue to become inflamed (red and swollen). However, one theory is that it may be due to the presence of cytokines in breast milk.

Cytokines

Cytokines are special proteins that are used by the immune system (the body's natural defence system) and are passed on to your baby to help them resist infection. It may be that your immune system mistakes the cytokines for a bacterial or viral infection and responds by inflaming the breast tissue (making it swell up) in an attempt to stop the spread of infection.

Infectious mastitis

Fresh human milk does not usually provide a good environment for bacteria to breed in. However, if the milk ducts become blocked, the milk can stagnate (lose its freshness from not moving) and an infection can occur.

Exactly how the bacteria enter the breast tissue has not been conclusively proven. Some suggestions are:

• bacteria that usually live harmlessly on the skin of your breast enter through a small crack or break in the skin
• bacteria that are present in the baby's mouth and throat are transferred during breastfeeding

You may be more likely to develop infectious mastitis if:

• your nipple is damaged, for example, from using a manual breast pump (a device used to express milk from your breast) incorrectly
• your baby has a cleft lip or palate (an opening or split in either their lip or in the roof of their mouth). This can also damage your nipple

Ducts
The tubes that transport milk in the breast.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Immune system
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Your GP should be able diagnose mastitis based on a physical examination of your breast and by asking you about your symptoms.

As mastitis is usually the result of problems with breastfeeding, your GP or midwife may ask you to demonstrate your breastfeeding technique. You should not feel as if you are being tested or blamed.  Breastfeeding can take time and practice to get right and sometimes you may need advice.

Breast milk sample

In some cases, your GP may take a small sample of your breast milk for further testing. This may be necessary if:

• you have severe mastitis
• you have been treated with antibiotics (medication to treat infections that are caused by bacteria) but they have not improved your condition
• you have had repeated episodes of mastitis 

Your breast milk can be tested to determine whether you have a bacterial infection and to identify the particular bacteria that is responsible. This can help to determine your treatment.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Antibiotics
Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi.

 

Mastitis can be easily treated using a number of self-care measures and by adjusting your breastfeeding technique. Most women make a full recovery very quickly.

Non-infectious mastitis

Most cases of non-infectious mastitis can be treated with a number of self-care techniques such as:

• making sure that you get plenty of rest
• drinking plenty of fluids
• using painkillers, such as paracetamol or ibuprofen that are available over the counter without prescription to reduce pain and fever (high temperature) - a small amount of paracetamol can enter the breast milk but it is not enough to harm your baby (aspirin is not safe to take while breastfeeding)
• not wearing tight-fitting clothing or a bra until your symptoms improve
• placing a warm compress (a cloth warmed with warm water) over your breast to help relieve the pain. A warm shower or bath may also help

Breastfeeding advice

Try to continue breastfeeding if you have mastitis. Following the advice below should improve your symptoms:

• keep breastfeeding or expressing milk by hand or with a pump (a device to help you express milk). If necessary, express milk between feeds
• feed from the affected breast often at least 8 to 12 times a day if you are only breastfeeding your baby (not bottle feeding as well)
• make sure that the breast is empty after feeds by expressing any remaining milk
• massage your breast to release any blockages. Stroke from the lumpy area towards the nipple to help the milk flow
• make sure that your baby is properly positioned and attached to your breasts. Your midwife or health visitor should be able to advise you about how to do this
• experiment with feeding your baby in different positions to see if this makes feeding more effective
• warming your breast using warm water can help to soften the breast, making it easier for your baby to feed

If your symptoms do not improve or they get worse despite trying these techniques, see your GP for additional advice or treatment.

Infectious mastitis

Infectious mastitis will need to be treated using a combination of the techniques outlined above and antibiotics (medication to treat infections caused by bacteria).

Your GP will prescribe an antibiotic that is safe to use during breastfeeding. This will usually be a tablet or capsule to take orally (by mouth) four times a day.

Antibiotics can enter the breast milk in very small doses and may affect your baby. For example:

• your baby may be irritable and restless
• your baby's stools may be looser (runnier) and more frequent

These effects are usually only temporary and will resolve once you have finished your course of antibiotics. They do not pose a risk to your baby.

Sore nipples

Your nipples may be sore if your baby is not properly attached during feeding. See the box to the right for sources of information that can help you to improve your breastfeeding technique.

If your nipples do not heal, return to your GP because you may have an infection. If you still have mastitis or pain in your breast, your GP may prescribe an oral antibiotic (see 'infectious mastitis', above).

Sore nipples may also be a sign of thrush, which is a fungal infection that is caused by the yeast fungus candida albicans. If you have thrush you may also have:

• a burning pain in your breast
• very itchy breasts
• pain that is worse at night or after feeding

Your GP can prescribe a cream for your breasts that you will need to apply after every feed for two weeks. Your baby may also need treatment if they have thrush in their mouth. See the Health A-Z topic about Oral thrush in babies for more information and advice.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Antibiotics
Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi.

 

In more severe cases of infectious mastitis, an abscess can develop in the breast. An abscess is a pus-filled space that can appear on the skin or inside the body.

Symptoms of an abscess include:

• a high temperature (fever) of 38C (100.4F) or above
• a very painful, swollen lump in your breast
• your breast may be red and feel hot

The abscess can be treated by draining the pus out of your breast. See the Health A-Z topic about Breast abscesses for more information about the condition.

One study found that three out of 100 women who were treated with antibiotics (medication to treat infections that are caused by bacteria) for mastitis developed an abscess. Some different research estimated that of the women who develop an abscess, one in 10 may be unable to breastfeed again.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Antibiotics
Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi.