Mastitis & blocked milk ducts

What is a blocked duct?

A blocked duct is an area or segment of the breast where milk flow is obstructed (milk stasis). This causes a reddened area or segment of the breast. The area can become tender, hard and painful. Sometimes it can be localised tenderness or pain without an obvious lump. It may occur with a white bleb/milk spot on the nipple. May occasionally have a low-grade temperature (less than 38.5 degrees celsius).

What is mastitis?

Mastitis, on the other hand, is a swelling (inflammation) of breast tissue caused by milk stasis. This is usually the result of a blocked milk duct – where milk isn’t moving and is slowed or stopped in one area of the breast.

Most of the cases of Mastitis are non-infectious (not bacterial) and may be treated using various methods included in the treatment below. Therefore, not ALL cases of Mastitis require immediate antibiotic treatment.

It is most common in breastfeeding women (Lactation Mastitis), although women who aren’t breastfeeding and men can also develop it.

How common is mastitis?

Nearly 1 in 5 breastfeeding women are affected by mastitis. In these cases, it usually develops in the first six to twelve weeks after giving birth.

Mastitis Symptoms:

  • Early signs of mastitis can be flu like aching, symptoms, including joint aches & pains, lethargy, shivering & chills.
  • Can appear very suddenly, ‘out of the blue’, while others start off with early signs of a painless blocked duct.
  • Thickening of breast tissue, swelling or a breast lump (sometimes hard to touch).
  • Breast tenderness, pain or a burning sensation continuously or during breast-feeding.
  • Generally feeling unwell.
  • The skin may be shiny and there may be red streaks. Skin redness is often in a wedge-shape.
  • Fever of 38.5 C or greater.
  • It usually affects one breast, but rarely can affect both.
  • A lump from a blocked/plugged duct may take a week or more to disappear completely. This may feel bruised and looks red after the acute mastitis has resolved.

Mastitis Causes:

  • A blocked milk duct that hasn’t cleared. If a breast doesn’t completely empty at feedings/pumping and milk remains in the milk tissue, one or more of your milk ducts can become clogged/blocked. The blockage causes milk to back up (becomes trapped in the breast), leading to breast infection. So the banked up milk behind the blocked duct is forced into the nearby breast tissue, causing the breast tissue to become inflamed.
  • Baby not being properly attached to your breast during feeding.
  • Incorrect size of breast shields so not draining well.
  • Bacteria living on your skin entering your breast. Bacteria from your skin’s surface and baby’s mouth can enter the milk ducts through a crack/damage on your nipple surface or through a milk duct opening. Stagnant milk in a breast that isn’t emptied provides a breeding ground for the bacteria.

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

Risk factors of blocked ducts & mastitis:

Factors that can cause poor milk drainage increases the risk for engorgement, plugged ducts, or mastitis.

  • Poor breastfeeding technique – Is the  latch-on and positioning optimal? Shallow, painful latch can affect milk drainage. Go back to the basics if need be.
  • Interrupted feeds, feeds being cut short or limited due to a busy schedule or if feeding patterns change abruptly, abrupt weaning.
  • Pressing down on the top or side of the breast to make extra breathing space for baby.
  • Anything that causes consistent pressure on breast tissue that can restrict/block milk flow.
  • Sleeping on one side or on your tummy.
  • Carrying too heavy a bag on one side.
  • Wearing your baby in a front carrier or sling for too long.
  • Wearing an ill-fitting or underwire bra or sleeping with a bra that presses in one area.
  • Wearing a seatbelt for too long.
  • Wearing constrictive clothing.
  • Oversupply (Too much milk).
  • Infants oral anatomy may hinder efficient breast drainage E.g. Ankyloglossia (Tongue Tie), Cleft Palate.
  • Use of a nipple shield can result in poor milk drainage from the breast.
  • Expressing too much (replacing missed breastfeeds), as breast pumps cannot always drain the breast as effectively as the baby can. If so, slightly move the breast shields around to different quadrants of the breast so these areas will be softened more efficiently.
  • Breast surgery can cause scarring and/or pressure on milk ducts.
  • Injuries to the breast (current & past) – roughly handling the breasts, scarring, knocked – can increase the risk of mastitis reoccurring in the same area of breast.
  • Exercise that involves repetitive movements of the upper arm.
  • Mother & baby separation.
  • Not having enough rest, becoming overly tired, unrelieved Stress, anxiety & fatigue. Mastitis can be a sign letting you know your body needs to slow down.
  • Poor nutrition – not eating regularly. Try and eat fresh foods to increase your resistance to infection.
  • Dehydration – Drink to thirst.
  • Avoid high saturated fat diet, reduce animal fat & limit polyunsaturated fats, use lecithin if you do.
  • Too high or too low salt can contribute to blockages.
  • Mother feeing unwell, has been ill, lowered resistance to infection, had issues with anaemia?
  • Smoking – can lower mothers’ resistance to infections.
  • Damaged/cracked nipples — although mastitis can develop without broken skin.
  • Milk bleb/white spot on nipples.
  • Secondary Infection, like Thrush (fungal/yeast infection), can cause inflammation within the milk ducts. 

Risk of blocked ducts/mastitis:

  • Inadequate treatment of current or previous mastitis.
  • Failure to completely recover from a previous bout of mastitis.
  • Delayed treatment of previous bouts of mastitis.
  • Incomplete treatment (not long enough) or incorrect antibiotic used.

Mastitis Prevention:

  • Fine tune your breastfeeding positioning and attachment. Having a good deep latch will help with good breast drainage. A lactation consultant (IBCLC) can give you the support and tips you may need.
  • Drain the breasts often, but gently. If the baby is unwell or not feeding efficiently, you may need to express to help drain the breast avoiding milk stasis. Learn to recognise good milk transfer and adequate swallows, sucking alone without swallows won’t help drain the breast. Treat any breast pain as soon as it becomes apparent, so it doesn’t become an infection.
  • Ensure your bra is comfortable and loose, or go without! Avoid wearing tight-fitting clothing until symptoms improve in general.
  • The more comfortable & relaxed, your mind and body is while breastfeeding, the better your breasts will flow with let-down. Try and breathe deeply and evenly, relax your arms, legs, back, shoulders and neck. Listen to soothing music and think about your baby to help start the let-down reflex.
  • Alternate/change breastfeeding positions you use, can help breasts drain effectively.
  • Avoid missing or putting off feeds -Breastfeed as often as your baby and breasts need to feed.
  • If a breast becomes uncomfortably full, wake baby for a feed, or express a small amount for comfort until baby is ready.
  • Avoid putting pressure on your breasts e.g. with uncomfortable clothing or with your fingers while feeding.
  • Rest as much as you can, at any opportunity you can.
  • Alternate from which breast you begin each feed, which helps to ensure at least one breast gets drained well at every second feed.
  • Avoid giving baby other fluids (even on hot days), your breastmilk is all it needs, unless medically indicated.
  • If prone to anaemia or had a bleed after delivery, chat to your OB or GP and organise a blood test to ensure your levels are ok, anaemia can put you at risk of Mastitis.
  • Eating well, increase foods containing natural sources of iron and Vitamin C and drinking to thirst, keep a water bottle close by while feeding. Have a basket with all your essentials, snacks, water, tissues, lip balm, phone and take the basket to wherever you feed!
  • Some bouts of blocked ducts or mastitis are associated with hormonal changes (menstruation or ovulation), if around these times, consider LECITHIN a fat emulsifier, may help reduce your risk of blockages. One theory is that if a mum has allergies, and is exposed to food allergens before ovulation or premenstrual, mum may be predisposed to blockages (complex immune responses).
  • Use lecithin daily if prone to recurrent mastitis or blocked ducts.

Mastitis Treatment:

Start treatment as soon as you have any signs or symptom of a blockage, pain or redness. Unless you have a temperature greater than 38.5oC you can often treat the blockage with various techniques first.

  • The symptoms of mastitis may discourage you from breastfeeding, unfortunately even if it is too painful to feed, this is not a time to wean. Your baby is usually very efficient (unless there are any oral anatomical issues) and can be the best to drain the breast for you. If your baby isn’t being effective, you may need to express to help drain the breast instead.
  • Frequent milk removal is an essential part of the treatment.
  • Your milk is safe for your baby to drink – So YES you CAN still breastfeed with Mastitis.
  • Start each feed from the affected breast, and feed more often on the affected side, especially for the first 12-24-hour period. Your baby may have a stronger sucking action when hungry at the beginning of the feed, which may help
    drain the affected area of the breast.
  • Aim to keep the affected breast as empty as possible (remembering our breasts are never empty but wanting them to be WELL DRAINED).
  • Take care not to let the other breast become too full, as it may cause a similar problem in that breast.
  • Check that your baby is actually transferring or getting the milk. Ensure the let-down reflex is working soon after s/he begins to suck (recognised by possible tingling feeling in the breasts, milk leaking from your other breast, or a sudden feeling of fullness. Babies sucking pattern changes and s/he will start to gulp or swallow more often).
  • TRY and ease into the feed ( difficult when in pain and or anxious), be as relaxed and comfortable as possible, to help your let-down reflex work.
  • Hand express or use an electric pump if you feel the baby is not draining well, or feeling full, before, after and between feeds if needed.
  • Ensure your baby is properly positioned and attached well. Your midwife, lactation consultant or MCHN can support you with fine tuning your latch.
  • Consider changing positions and pointing baby’s chin to the blockage, to help with better drainage, experiment using other feeding positions which may help with better drainage of the blockage.
  • Use heat sparingly for a up to 10 minutes (warm shower, heat/wheat pack, hot water bottle, warm face washer) on the area prior to a feed (can help stimulate your letdown assisting your milk to flow, to help drain breast).
  • Apply cold packs on the affected breast after a feed, which may help relieve pain and reduce swelling. Treat like a sprain, use cold pack 20min on, 20 min off and repeat as often as you can.
  • Massage the breast gently by stroking from behind the lumpy area toward the nipple while baby feeds, helping the milk flow releasing blockages. Try using the back of an electric toothbrush if too painful to touch or handle, or a wide tooth comb stroking the breast toward the nipple.
  • Use some THERAPEUTIC ULTRASOUND offered by a women’s health physio to help break up the blockage/s.
  • Ensure you get plenty of rest, tuck yourself into bed with your baby (safely) and do nothing but feed and rest (often easier said than done!). Get help, you’ll need someone to care for bubba while you are sleeping and bring baby to you when hungry. Rest is essential to get better. It can really knock you about! Keep everything you need (food, water, nappies etc) close by you to save you getting up.
  • Keeping fluids up, stay well hydrated & eat healthy.
  • To help reduce the pain, fever and inflammation, keep up anti-inflammatory (ibuprofen) & pain relief (paracetamol).
  • Only a minimal amount enters breast milk, not enough to harm your bubba.

Seek meedical support if you:

  • Are running a temperature greater than 38.5oC (with associated pain, blockage etc).
  • Have had 12 – 24 hours of using various techniques outlined above, with no improvement or resolution to your symptoms your blockage may have become infective mastitis. 
  • Are suffering a lot of pain and it is becoming difficult to breastfeed.

Your GP will assess and prescribe appropriate antibiotics. Know that prescribed medication is SAFE for a breastfeeding mother and baby. Used to treat the infection caused by bacteria, it is safe to continue breastfeeding or expressing and using the expressed breast milk in a bottle. DO NOT THROW YOUR BREASTMILK AWAY.

  • Flucloxacillin (or dicloxacillin 500mg 6 hourly) is usually the drug of choice for 7-10 days unless allergic to penicillin (then Cephalexin) – 500mg 6 hourly at least 5 days) as per RWH Clinical Guidelines.
  • FINISH the antibiotic course prescribed.
  • A very small, safe amount of the antibiotic may enter your breast milk and may make your bubba
    temporarily a little restless or irritable. It may make change babies poos a little runny and more frequent, will resolve few days following antibiotics have ceased.

Other important factors to consider:

  • Prompt, early, adequate treatment of Mastitis and/or a blocked duct will mean you get better faster. You will feel less ill and you will be at less risk of more serious complications like a breast abscess (a painful collection of pus).
  • If your Mastitis is persistent or severe, your doctor may take a small sample of your breast milk for testing (especially if it is your 2nd or 3rd episode using the same antibiotics). This breastmilk sample helps to ensure treatment with appropriate antibiotics).
  • Some GPs may test for nipple thrush if a damaged area on the nipple isn’t healing. Antibiotics can trigger a candida/thrush infection in your breast or in/on your nipple (especially if you are prone to thrush & have a candida overload).
  • While probiotics may not prevent mastitis, you can use them daily to replace the good bacteria that will be killed by the antibiotics and help to prevent a vaginal or nipple/breast yeast infection.
  • If symptoms are not resolving, you may need to go back to the GP/OB who may order a diagnostic ultrasound to ensure a breast access has not developed.
  • If a breast abscess is found (about 3 % of mastitis), the area of blockage may need to be treated (aspirated) by either a GP in their rooms, or surgically drained by a breast surgeon.
  • The milk from the affected breast may taste salty. This won’t harm your baby and is safe to drink, but may cause him/her to refuse or become fussy at the breast. Any bacteria present in the milk will be harmlessly absorbed by the baby’s digestive system and will not cause any problems.
  • You may notice that any expressed breastmilk looks lumpy, stringy, like gelatine.
  • Some will strain out the ‘lumps’ from expressed milk. Milk can also contain mucus, blood, or pus. Still SAFE for your baby to have (Remember, that if baby was breastfeeding you wouldn’t know the milk was bloodstained or stringy/lumpy!).
  • Lactation mastitis may cause you to feel run down, and makes it difficult to care for your baby. Reach out for support at this time, especially if you have a toddler.
  • Mastitis can lead to a mother weaning her baby before she intends to. Having mastitis can impact on a mother’s milk supply, and if she already had a low milk supply it can drop further. This may need some attention/support with increasing your breastmilk supply, it is usually only temporary for most mothers.


  • Mastitis | Australian Breastfeeding Association
    Blocked ducts | Australian Breastfeeding Association
  • Mastitis | The Royal Women’s Hospital
  • Mastitis – Symptoms and causes – Mayo Clinic
  • Plugged Ducts and Mastitis • KellyMom.com
  • Plugged Duct or Mastitis – Extended Breastfeeding Fact Sheet
  • Blocked milk ducts and mastitis fact sheet | Children’s Health
  • Breastfeeding and breast abscess
  • KellyMom.com
  • Lecithin treatment for recurrent plugged ducts • KellyMom.com
  • Recurrent Mastitis or Plugged Ducts • KellyMom.com

~ Susan Shaw, Lactation Consultant

You can find more about Susan here: http://www.susanshaw.com.au

You may be interested in these post-natal blogs by our Physiotherapists:




Recent Posts