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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.
Read more about the symptoms of mastitis.
You should visit your doctor 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, see breast lumps for more information.
Read more about how mastitis is diagnosed.
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.
Read more about the causes of 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:
Read more about expressing and storing breast milk.
All cases of infectious mastitis will need to be treated with antibiotics to bring the infection under control.
Read more about treating mastitis.
Although the symptoms of mastitis may discourage you from breastfeeding, it is important that you try to continue. Regular breastfeeding will help:
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.
Mastitis should be promptly treated to prevent more serious complications developing , such as a breast abscess (a painful collection of pus).
Read more about the complications of mastitis.
Mastitis usually only affects one breast and symptoms often develop quickly.
These symptoms include:
Over half of women with mastitis may also experience flu-like symptoms such as:
Visit your doctor immediately if you experience these symptoms, and you also have a red, tender area on your breast.
Mastitis is not usually a serious condition, but advice and prompt treatment may be needed to stop the condition getting worse.
Speaking to your doctor or midwife will also help to reassure you.
Mastitis can have different causes depending on whether it is infectious or not.
Most cases of non-infectious mastitis are thought to be caused by milk stasis. Milk stasis occurs when the milk is not properly removed from your breast during breastfeeding. It can be caused by:
Milk stasis can cause the milk ducts in your breasts to become blocked.
Experts are not sure why breast milk can cause the breast tissue to become inflamed. However, one theory is that it may be due to the presence of special proteins called cytokines in your breast milk.
Cytokines are proteins used by the immune system. They are passed on to your baby to help them resist infection.
It may be that your immune system mistakes cytokines for a bacterial or viral infection and responds by inflaming the breast tissue in an effort to stop the spread of infection.
Fresh human milk does not usually provide a good environment in which bacteria can breed. However, if your milk ducts become blocked, milk can stagnate and an infection can develop.
Exactly how bacteria enter the breast tissue has not been conclusively proven. It may be that:
You may be at greater risk of developing infectious mastitis if:
In women who don't breastfeed, mastitis is caused by an infection.
This can be due to bacteria getting into the milk ducts through a cracked or sore nipple, or a nipple piercing.
There are two different types of mastitis that affect women who are not breastfeeding. These are:
Your doctor should be able diagnose mastitis after examining your breast and asking about your symptoms.
As mastitis is usually the result of problems with breastfeeding, your doctor 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.
If you're not breastfeeding, your doctor will want to rule out other conditions as a breast lump can be a sign of breast cancer.
Your doctor may decide to take a small sample of your breast milk for testing. This may be necessary if:
Your breast milk can be tested for a bacterial infection and to identify the bacteria responsible. This will help to determine your treatment.
Mastitis can usually be easily treated and most women will make a full recovery very quickly.
Most cases of non-infectious mastitis can be treated using a number of self care techniques such as:
You should try to continue breastfeeding if you have mastitis. Following the advice outlined below should improve your symptoms.
Visit your doctor for additional advice or treatment if your symptoms do not improve or they get worse despite trying these techniques.
Infectious mastitis will need to be treated using a combination of the above techniques and antibiotics (medication to treat infections caused by bacteria).
If you are breastfeeding, your doctor will prescribe an antibiotic that is safe to use. This will usually be a tablet or capsule that you take orally (by mouth) four times a day.
A very small amount of the antibiotic may enter your breast milk and may make your baby irritable and restless or your baby’s stools looser (runnier) and more frequent.
These effects are usually temporary and will resolve once you have finished the course of antibiotics. They do not pose a risk to your baby.
Your nipples may become sore if your baby is not properly attached during feeding. Your doctor, midwife or health visitor will be able to advise about [how to improve your breastfeeding technique].
If your nipples do not heal, you should return to your doctor because you may have an infection. If you still have mastitis or pain in your breast, your doctor may prescribe an oral antibiotic (see above).
Sore nipples can also be a sign of thrush, a fungal infection caused by the yeast fungus, Candida albicans. If you have thrush, you may also have:
Your doctor may prescribe a cream that you will need to apply to your breasts after every feed, for two weeks. Your baby may also need to be treated if they develop thrush in their mouth.
Read more about oral thrush in babies.
In severe cases of infectious mastitis, an abscess can develop in the breast.
A breast abscess is a painful collection of pus that forms in the breast, just under the skin.
As well as causing a painful lump to develop, a breast abscess may also:
The abscess can be treated using a needle or a small incision to drain the pus out of your breast.
Read more about breast abscesses.
One study found that 3 out of 100 women who were treated for mastitis with antibiotics (medication to treat infections caused by bacteria) developed an abscess. Some different research estimated that 1 in 10 women who develop an abscess may be unable to breastfeed again.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.