What is mastitis?
Mastitis is an inflammation of the breast which can cause a collection of distinctive symptoms ranging from a sore, painful breast to flu-like symptoms. Mastitis is the body’s reaction to a build up of breast milk sitting in the breast (milk stasis). If the pressure of milk in the breast gets too high—when breasts are over full or engorged—it is thought that some of the components of breast milk leak into the surrounding breast tissue causing inflammation. Mastitis is a relatively common condition affecting breastfeeding women.
This article looks at the symptoms and causes of breastfeeding related mastitis, and how to prevent and treat it.
Symptoms of mastitis
The symptoms of mastitis can include:
- Soreness, pain, heat and swelling (inflammation) in the breast
- A sore lump or tender spot inside the breast
- Areas of red or pink skin on the surface of the breast, may include red streaks or lines. Colour changes seen on lighter skin tones during mastitis may not be visible on darker pigmented skin.
- Flu-like symptoms such as feeling achey, shivery or run down, headache
- Bacterial infection (may or may not be present)
- Increased sodium levels in breast milk making it taste saltier
- Usually affects one breast, rarely both breasts
- Some mothers notice pumped breast milk can be lumpy or clumpy1
Mastitis is not always associated with a bacterial infection. When there isn’t a bacterial infection, mastitis symptoms often clear on their own after a day or two of careful preventative treatment—see the “Mastitis action plan” below. If a bacterial infection is present, this is usually due to Staphylococcus aureus (Staph). Where mastitis affects both breasts, the cause may be Streptococcus (Strep) 2. The US based Academy of Breastfeeding Medicine explains:
The usual clinical definition of mastitis is a tender, hot, swollen, wedge-shaped area of breast associated with temperature of 38.5C (101.3F) or greater, chills, flu-like aching, and systemic illness. However, mastitis literally means, and is defined herein, as an inflammation of the breast; this inflammation may or may not involve a bacterial infection. Redness, pain, and heat may all be present when an area of the breast is engorged or ‘‘blocked’’/‘‘plugged,’’ but an infection is not necessarily present. There appears to be a continuum from engorgement to non infective mastitis to infective mastitis to breast abscess.
What causes mastitis?
Causes of mastitis typically include anything that prevents frequent and thorough milk removal:
- A baby who is not emptying the breast properly—causing engorgement or blocked ducts e.g. a baby with a shallow latch, or using a poorly fitted nipple shield.
- A baby who is not emptying the breast often enough, perhaps due to scheduled feeds, use of a pacifier, separation of mother from baby for several hours, or the first time a baby sleeps through the night
- A baby who is feeding less due to illness
- Abrupt weaning
- Anything pressing on the glandular tissue in the breast which could interfere with milk flow such as a tight bra or other clothing, the straps of a heavy bag or even mother’s sleeping position or a finger pressing firmly into the breast throughout a feed
- A true oversupply of breast milk
- A stressed mother who is trying to do too much or who is run down, poorly or not eating properly (Wambach and Spencer 2021. p 285).
Further risk factors for mastitis include:
- Smoking increases the risk of breast abscess and inflammation in the ducts behind the nipple (breast periductal inflammation.34
- Sore, cracked nipples prior to the mastitis episode (Foxman et al, 2002) or nipple damage from a nipple piercing or skin infection (NICE 2021).
- Breast trauma if the duct and gland tissue are damaged (NICE 2021) including previous breast surgery e.g. breast implants, reduction surgery or any other causes of scarring within the breast or nipple.
- A history of mastitis 5
- Diet and inflammation. Eating a high proportion of inflammatory omega-6 polyunsaturated fatty acids (PUFAs) while having very few anti-inflammatory omega-3 PUFAs may promote inflammation in the body including breast tissue. In addition a diet high in refined sugar, saturated fats and low in fibre discourages a healthy microbiome (friendly bacteria within our bodies) favouring bacteria that may contribute to inflammation and disease instead.67
- Using nipple creams and gel pads 8 including using antifungal cream, either due to thrush or perceived thrush (Foxman et al, 2002).
- Use of a manual breast pump during the same week as the mastitis episode (Foxman et al, 2002)
- Use of a nipple shield may be associated with blocked ducts or mastitis if a baby finds it difficult to drain the breasts thoroughly with the shield in place.
- A mother who does a lot of vigorous exercise especially using the upper arms and chest (Wambach and Spencer, 2021 p 285).
Ideas to prevent mastitis include:
- Good breast drainage. Breastfeeding frequently on demand with your baby in a deep, comfortable latch and hand expressing or pumping to comfort at the first sign of engorgement or a blocked duct can help prevent mastitis. One study found that 85% of cases of inflammatory symptoms of the breast resolved with latching help to ensure effective milk removal.9 For more information about preventing engorgement and how to deal with it see Engorged Breasts and Blocked Milk Duct.
- Light touch massage. Careful use of very gentle light touch massage including the use of therapeutic ultrasound may help to drain an engorged breast thoroughly to prevent mastitis developing.10
- Sore nipple care. Sore, cracked nipples may increase the risk of a breast infection so washing damaged nipples daily with a mild soap is another preventative measure—see Treatments for Sore Nipples
- Diet. One study found that eating traditional fermented foods such as kefir or homemade yoghurt may be protective against mastitis. 11
If you have mastitis it’s important to take action quickly to keep milk flowing, reduce engorgement and keep comfortable—see the ideas in the action plan below. If you don’t see any improvement after 12-24 hours, check with your doctor in case antibiotics may be needed.12
Mastitis action plan
- Check latch and positioning—see Breastfeeding Positions for Newborns, Breastfeeding Videos and Latching Tips or seek help from your IBCLC lactation consultant or breastfeeding specialist to get your baby’s latch just right—both to aid a speedy recovery and to prevent mastitis coming back again.
- Empty the breast—continue to breastfeed as often as you can to empty the affected breast of milk—while not forgetting the other breast must also still be drained regularly. If your baby can’t empty the breast by breastfeeding, or if it is too painful to breastfeed, you will need to hand express or pump to remove enough milk until you feel comfortable again.
- Moderate warmth on the breast can help trigger the let down before you breastfeed or express. Warmth can also help with pain relief.13
- Cold ice packs. A cold compress such as frozen peas or crushed ice in a damp cloth placed against the sore, and engorged areas for up to 20 minutes at a time will help reduce breast inflammation between feeds. Many mothers have found that chilled cabbage leaves slipped inside the bra cup around the affected breast can also soothe the area.
- Compatible pain-killers or anti-inflammatory medication will help with the pain and inflammation.
- Light touch massage combined with hand expression may help milk and other fluids in the breast (lymph fluid) to flow (Morgensen et al, 2020). However any massage technique should use no more pressure than applying cream to the skin or stroking a pet. A deep or vigorous massage could traumatize a breast and worsen engorgement and inflammation. For a summary of gentle massage techniques for engorgement see Engorged Breasts, and Blocked Milk Duct.
- Rest, remember to eat and drink plenty of fluids. Lawrence and Lawrence state bed rest should be mandatory during mastitis.14.
- Check with your health care professional if there is no improvement after 12-24 hours.
A note on using heat
Warmth can be soothing and provide pain relief. It may also help with the let down. However bear in mind too much intense heat on the breast could potentially cause blood vessels to widen (dilate) and bring even more fluid to the area adding to any engorgement. For more information about preventing engorgement and how to deal with it see Engorged Breasts.
When should I see my doctor?
If you are not starting to feel better after 12-24 hours of treatment and if you have any of the symptoms in the following excerpt, contact your health care professional for advice.
When you have mastitis… Talk to your [doctor] about starting antibiotics immediately if:
- Mastitis is in both breasts.
- Baby is less than 2 weeks old, or you have recently been in the hospital.
- You have broken skin on the nipple with obvious signs of infection.
- Blood/pus is present in milk.
- Red streaking is present.
- Your temperature increases suddenly.
- Symptoms are sudden and severe.
Medication for mastitis
Ibuprofen and paracetamol are compatible with breastfeeding 15. The Academy of Breastfeeding Medicine explains:
Analgesia [Painkillers]. Analgesia may help with the let-down reflex and should be encouraged. An anti-inflammatory agent such as ibuprofen may be more effective in reducing the inflammatory symptoms than a simple analgesic like paracetamol/ acetaminophen. Ibuprofen is not detected in breast milk following doses up to 1.6 g/day and is regarded as compatible with breastfeeding.
Your health care professional will be able to prescribe compatible antibiotics for a bacterial infection if symptoms are not improving after 12-24 hours of a mastitis action plan, or if the mother is very poorly 16. The organisations below discuss specific antibiotic choices and doses and currently recommend a 10–14 day course of antibiotics:
- Management of mastitis and breast abscess in lactating women. NICE, 2021 (UK based)
- ABM Clinical Protocol #4: Mastitis, Academy of Breastfeeding Medicine, Revised March 2014 (USA based)
Nisin is an antibacterial peptide produced by the bacterium Lactococcus lactis that kills other bacteria and is used as a food preservative. One study found swabbing nipples with a nisin solution was an effective alternative to antibiotics in treating mastitis due to stahylococcus.17
The results of studies on the use of probiotics to prevent or treat mastitis are not clear. Arroyo et al 18 compared giving mothers strains of Lactobacillus species isolated from breast milk with conventional antibiotic treatment. They found that women who took the probiotics improved more and had lower recurrence of mastitis than those who took antibiotics. Another industry funded study found improvement in the risk of mastitis after giving the mothers a probiotic.19 However, Amir et al 20 describe a number of concerns about the validity of Arroyo’s study, and similar trials, and call for high quality randomised control trials to establish whether probiotics are an effective treatment for mastitis.
The food supplement lecithin may help to reduce the constituency (thickness) of breast milk reducing the risk of blocked ducts and associated mastitis.21
If you keep getting episodes of mastitis or blocked ducts an IBCLC lactation consultant or breastfeeding specialist can be very helpful to identify the most likely reasons why. They will review your history, and check whether your positioning, latch or breastfeeding management could be the cause for mastitis to keep returning. Other risk factors for recurring mastitis include:
- Incomplete treatment of the original infection or mastitis which is not treated promptly or had less than 10 days treatment with antibiotics22
- Mothers who have a previous history of mastitis 23.
- Breastfeeding on a schedule instead of whenever baby wants (on demand)
- Stopping breastfeeding abruptly on the affected side during an episode of mastitis
- Recurring blocked ducts
- Mother being anaemic or very stressed 24
- Dietary fats. Recurrent blocked ducts and associated mastitis may be worsened by a diet that is rich in saturated fats (see above) and eating more polyunsaturated fatty acids and adding lecithin to the mother’s diet may be helpful (Lawrence, 2016).
- Deep or vigorous massage could traumatise delicate breast tissue and may cause more inflammation (Morgensen et al, 2020).
Treatment for recurrent mastitis
Doctors Lawrence and Lawrence 25 recommend antibiotic treatment should continue for at least 10-14 days to prevent recurrence. If it does come back again, they advocate:
- Culture specimens from breast milk and from the baby’s nose and throat. NICE guidelines advocate taking a swab for culture from both mother and baby’s nose in addition to a breast milk culture (NICE, 2021).
- Fully review the circumstances and possible causes of recurrence (an IBCLC lactation consultant can help with this)
- Adequate rest, nutrition, fluids and stress management for mother
- Complete breast drainage by baby or pump
- Consider chronic bacterial infection, pseudomonas infection, secondary fungal infection, underlying breast disease such as a cyst, tumour or other medical cause.
In addition to checking breastfeeding latch and positioning with a breastfeeding specialist, the NICE website includes the following tips to prevent mastitis from recurring:
- Avoid missing feeds, avoid using a dummy, breastfeed as often as baby wants (on demand)
- Be aware of signs of engorgement and how to hand express if needed
- Ensure pumping equipment is washed thoroughly with soap and hot water after every use
- Discard any potentially contaminated nipple creams or ointments
- If stopping breastfeeding, do not stop abruptly, express enough milk to stay comfortable.
With breastfeeding challenges there is sometimes more than one thing going on at the same time. If mastitis does not seem to respond to treatment or keeps recurring there may be something else involved. For a review of other causes of deep breast pain associated with breastfeeding see Why Does Breastfeeding Hurt? and see below.
Other causes of breast inflammation
The term subacute mastitis has been used in some papers however there is no clear definition between authors. Jiménez et al put forward a theory for subacute mastitis due to specific strains of bacteria that cause inflammation of the ductal system without the classic symptoms of mastitis that may be mistaken for a fungal infection (thrush).26
Fungal infection has historically been described as a cause of deep breast pain27 however more recent research highlights multiple other conditions to explain these symptoms casting doubt on breast thrush28
Check with your health professional if mastitis does not improve with treatment. Although rare, other conditions such as cellulitis or inflammatory breast cancer can be mistaken for mastitis.29
Frequently asked questions
#1 Can I continue breastfeeding my baby if I have mastitis?
Yes, even if antibiotics are needed, breastfeeding can continue during mastitis.30 Antibodies in breast milk will help protect the baby from any infection and stopping breastfeeding abruptly could cause more problems. Breast milk may taste slightly salty from a breast with mastitis but this doesn’t usually pose a problem to the baby.
There is no evidence of risk to the healthy, term infant of continuing breastfeeding from a mother with mastitis. Women who are unable to continue breastfeeding should express the milk from breast by hand or pump, as sudden cessation of breastfeeding leads to a greater risk of abscess development than continuing to feed.
Most cases of infection based mastitis are caused by Staphylococcus aureus bacteria (staph). For more information about breastfeeding and staph infections including infection by methicillin-resistant Staphylococcus aureus (MRSA) see Staph, MRSA and Breastfeeding.
#2 What can I do if my baby can’t latch or my milk won’t flow?
Sometimes engorgement behind the nipple can change the nipple shape making it difficult for your baby to latch and having the effect of someone stepping on a hose, stopping the flow of liquid (i.e. breast milk!). If you’re struggling to express any milk at all or your baby can’t seem to latch due to engorgement, have a look at Engorgement Relief When Milk Won’t Flow for ideas to help you.
#3 What is the treatment for blocked milk ducts?
An untreated blocked duct can lead to mastitis. Treatment for a blocked duct is very similar to treatment for relieving engorgement or mastitis, but lecithin and other supplements are sometimes suggested, see Blocked Milk Duct for more information. If you have a white spot on your nipple alongside symptoms of mastitis, see the section about milk blisters or blebs in Blisters on Nipples for ideas of how to clear it.
#4 Bra or no bra?
It’s important to ensure a tight fitting bra is not the cause of the mastitis. NICE guidance recommends avoiding wearing a bra, especially at night31 whereas Lawrence and Lawrence say to wear a supportive bra during mastitis that doesn’t cause painful pressure (Lawrence, 2016).
#5 Why is my breast milk thick or lumpy?
If milk has a thick or clotted consistency within the breast this could be a risk factor for blocked ducts and mastitis. Does thickened milk cause blocked ducts/mastitis or does mastitis cause thicker, lumpy milk? Explanations for thickened milk include poor breast drainage, a mastitis infection and dietary factors.
- Breast drainage and milk consistency. Whenever areas of the breast are not thoroughly and frequently drained of milk there is a risk that the milk could thicken and cause blocked ducts. See Blocked Milk Duct for more information on the causes and ideas for treating a blocked duct.
- Mastitis and lumpy clumpy milk. Some mothers may notice their expressed breast milk has lumps or clots in it. These may seem to form in the collection container just after pumping, or seem to come directly from the nipple. In The Breastfeeding Atlas, 6e, p97 authors Wilson-Clay and Hoover share that clumpy, lumpy milk is an indication of early mastitis in the dairy industry and could also be linked to breast inflammation in humans as some women have reported clumpy milk during mastitis episodes. The cause of the lumpy milk may be a result of coagulase, a protein made by Staphylococcus microorganisms that produce fibrin; a substance that causes clotting.32 A culture of the lumpy milk may locate a particular organism for treatment.
- Diet and milk consistency. Unless a mother expresses her milk the presence of thicker or lumpy breast milk and whether it could sometimes be a variation of normal would not be apparent. However if blocked ducts are problematic; Lawrence and Lawrence suggest eating more polyunsaturated fats and adding lecithin (an oily food supplement) to the diet can help reduce the consistency of breast milk and so reduce frequency of blocked ducts or repeated episodes of mastitis33.
Mastitis is the name for an inflammation in the breast. During breastfeeding, mastitis is the body’s reaction to a build of breast milk that is not getting drained from the breast. Mastitis can be very painful and a mother may have general symptoms similar to flu (shivers, temperature, feeling unwell) as well as a very painful sore breast (or two). At the first sign of engorgement—breastfeeding, pumping, or hand expressing until the breast is comfortable again can help to avoid mastitis. Sometimes mastitis is associated with a bacterial breast infection and requires antibiotics. There are several antibiotics for treating mastitis that are compatible with breastfeeding—it is important not to stop breastfeeding or stop frequent milk removal during an episode of mastitis or it could develop into a breast abscess. If mastitis keeps coming back, check your baby’s latch and positioning with your breastfeeding specialist or IBCLC lactation consultant and contact your medical professional.