Plugged (Blocked) Ducts And Mastitis

Plugged (Blocked) Ducts And Mastitis

Plugged (Blocked) Ducts And Mastitis

A plugged (blocked) duct makes breasts throb and ache. It can lead to mastitis if it's not cleared. Learn how to relieve a blockage and minimize the risk of reoccurrence.

Plugged ducts 

Each breast contains a complex system of milk (mammary) ducts that convey the milk from the milk secreting glands, called alveoli, to the nipple. Certain conditions can lead to a milk duct becoming temporarily plugged or blocked. The blockage then causes milk to backlog in the breast; pressure builds up and the milk leaks into adjoining tissue, causing a tender, lumpy area in the breast. 

A plugged duct is more commonly found where there is an oversupply of milk from breast engorgement, missed feeds or the breast not being fully emptied, or where some form of constriction prevents the milk from passing through a duct to the nipple. Occasionally a tiny white plug can be seen at the opening of the nipple, but a plugged (blocked) duct can also develop further back in the breast.

Although it can be painful a plugged duct is not a serious condition. As there is no infection involved women generally feel well. However, if left untreated a plugged duct may lead to mastitis (but not always).


Mastitis is an infection of breast tissue, in particular the milk ducts and glands of the breast. It is usually due to bacteria entering the breast through a cracked nipple, but women without sore nipples can also get mastitis. When a milk duct is plugged (blocked) there is an increased risk of mastitis occurring, as stagnant milk provides a perfect environment for bacteria to flourish.

Mastitis is a very painful condition. Because an infection is involved, a woman can quickly become unwell with fever, aches and chills. In situations where symptoms last for longer than 24 hours antibiotic treatment is necessary in order to reduce the risk of a breast abscess developing.

Mastitis occurs in approximately 1 in 40 nursing mothers. Mastitis can also occasionally develop in pregnant women and small babies.

Signs & Symptoms

Plugged (blocked) ducts

  • Comes on gradually.
  • Pain is mild and normally localized.
  • Firm lumps can be felt but they are not hot to touch.
  • The area may be reddened (but not always).
  • May have a temperature lower than 101° F (38.4° C).
  • You generally feel well. 


  • Comes on suddenly.
  • Intense pain in one or both breasts (generally only one).
  • All or part of the breast can become painful, red, hot and swollen.
  • Skin may appear tight and shiny, and be streaked with red.
  • Temperature reaches 101° F (38.4° C) or higher.
  • The nipple may be sore or cracked (but not always).
  • You may feel like you are coming down with the 'flu' i.e. aches and chills and feeling run down.  (Without other symptoms listed here you may have the flu rather than mastitis.) 

NOTE:  A thrush infection can cause breast pain that is often described as a hot knife or hot shooting pains in the breast. Unlike mastitis there is no associated area of hardness. Because thrush is an infection due to a yeast-like fungus (Candida albicans) and not bacteria it should not be treated with antibiotics.


A plugged (blocked) duct

No one knows the specific cause of a plugged duct or why some women are predisposed to them and others never encounter the problem. Nevertheless, contributing factors, which increase the risk of a plugged duct developing, have been identified. These include...

  • A poor latch-on of the baby or incorrect sucking.
  • Poor positioning of the baby.
  • An oversupply of milk due to engorgement; missed feeds, giving bottles in place of breastfeeds or skipping pumping sessions when separated from the baby.
  • A tight or ill-fitting bra (particularly under-wire bras).
  • Consistently lying in one position during sleep.
  • A baby carrier or seat belt that cuts into breast tissue.
  • Holding the breast too tightly during feeding.
  • Massaging the breast vigorously with finger tips.


It is known that mastitis is usually caused by a common bacteria Staphylococcus aureus and Eschericha coli. Staphyloccus areus that is found on normal skin and nasal passages of 25% to 30% of the population, Eschericha coli is a common inhabitant of the bowel.

The following circumstances increase the risk of mastitis developing...

  • Milk stasis due to an untreated plugged milk duct.
  • An abrupt change in the frequency of feeding.
  • Poor physical health.
  • Poor nutrition.
  • Inadequate hand-washing.
  • Stress and fatigue.
  • Cracked or damaged nipples.
  • Using wet nursing pads for long periods when you have sore or cracked nipples, particularly those with a plastic lining.

What to do 

By taking active steps to improve the drainage from the breast, a plugged duct and/or mastitis will usually improve in 24 to 48 hours. 

What to do for plugged ducts

  • Before breastfeeding, heat your breast by placing a hot pack on the affected area for 60 seconds or longer. (You can make a hot pack by adding 1 cup of water to a disposable diaper and heating it in the microwave. Then mould the diaper around your breast for 60 seconds).
  • After heating your breast gently massage the affected area with stoking movements towards your nipple.
  • (Also massage while your baby feeds).
  • Offer your baby the affected breast first.
  • Make sure your baby is properly latched-on.  (See Breastfeeding basics).
  • Position your baby so that her chin is over the affected area.  This is where the most suction is applied.
  • Change your baby's feeding position at least once per day.
  • If the duct has not cleared with feeding, hand express or pump after your baby has finished feeding.  (Always offer her the breast first).

What to do for mastitis

  • Take acetaminophen (paracetamol) or ibuprofen to relieve pain.
  • Follow the steps above to keep your affected breast well drained.
  • See your doctor as soon as possible. If your fever continues for more than 24 hours, he/she may prescribe an antibiotic compatible with breastfeeding.
  • If it hurts to breastfeed your baby, start feeding on the breast that is not sore and switch to the sore breast after your milk lets down.  If it is too painful to feed from the affected breast, hand express or pump your milk as best you can and restart breastfeeding as soon as you can. 
  • Heat your breast before feeding (as described above) and cool your breast after feeding with a cool pack (a packet of frozen peas works well).
  • Go braless where you can, so as not to put pressure on the affected area.
  • Rest as much as possible.
  • Keep to a nutritious diet and plenty of fluids.
  • Treat cracked nipples.
  • Don't quite nursing at this point. Many women are tempted to quit due to the severity of pain but with appropriate treatment (as described above) the pain will pass within a few days. Breastfeeding is the fastest way to improve mastitis.


Recurrent episodes of mastitis may mean your immune system is run down because of fatigue, stress or poor nutrition. 

  • Take care with breast hygiene and hand-washing to prevent the area becoming exposed to bacteria.
  • Treat breast engorgement and cracked nipples promptly.
  • As a poor latch-on is the leading cause of most breast problems, making sure you have a correct latch-on is the most important step towards prevention of mastitis. Seek the support of a breastfeeding counselor who can observe your baby's latch-on and provide advice on improving your technique.
  • Keep your breasts draining by pumping or waking your baby for a feed if she sleeps for long periods.
  • For an oversupply, try feeding from one breast only at each feed.
  • Be aware of anything that may constrict your breast too tightly.
  • Take care of yourself. Attend to your nutritional needs. Eat regular small nutritious meals.
  • Avoiding caffeine and smoking may also help.
  • Review your lifestyle. Are you trying to do too much? Is there any way to reduce your load?


1. Should I stop feeding until the infection has improved? 

Don't stop breastfeeding as this will increase the risk of a breast infection (mastitis) turning into a breast abscess that requires surgical draining. If breastfeeding is not possible, hand expressing or pumping is necessary to drain the breast

2. Is it safe for my baby to drink the milk from the infected breast?

There is no significant risk to your baby from the infection or from commonly prescribed antibiotics.

3. Will mastitis affect my lactation?

After the infection has cleared the affected breast undergoes a 'recovery phase' and usually produces less milk temporarily. However, milk supply will generally pick up quickly once latch-on has improved. 

Poor latch-on is not only the leading cause of mastitis it is also the leading cause of low milk supply. If a poor latch-on is not corrected milk supply may reduce dramatically for this reason. 

4. Do all cases of mastitis require antibiotic treatment?

Once milk drainage has improved mastitis will improve quickly.  Due to the associated side effects of antibiotic medications many doctors only recommend antibiotic if the infection has not shown signs of improvement after 24 hours. Your doctor will be the best person to advise if antibiotics are necessary, based on your individual circumstances. 

5. Will antibiotics alone fix the problem?

Antibiotics should not be the only treatment used. Mastitis is a sign of an underlying problem, such as poor drainage due to incorrect latch-on. If the source of the problem is not corrected there is a strong possibility that mastitis will return in the future.

6. Will antibiotics affect my baby?

Antibiotics can pass through your breast milk to your baby.  Your baby may experience side effects such nausea, diarrhea, vomiting or an allergic reaction, e.g. rash, or she may fuss with feeding due to the altered taste of your milk.

It's very important to complete the full course of antibiotic treatment to reduce the risk of relapse. See your doctor if you or your baby experience side effects.  He/she may be able to prescribe a different antibiotic with fewer side effects.

7. What do I do if my baby refuses to feed from the infected breast?

There could be a number of different reasons why your baby may refuse or fuss at the breast. Your baby may experience difficulty latching on due to breast engorgement. In this situation hand express or pump a little milk before latching on to soften the area around the nipple.

Your baby may fuss because the taste of your milk has changed. If your baby is latching on okay but fusses only at the affected breast, it may be related to the fact that the sodium content in your milk will rise when mastitis is present, making your milk taste salty. If your baby fusses with both breasts it may be due to the taste of the antibiotics.

If your baby refuses to feed from your breast you will need to hand express or pump approx. every 3 hours. It's fine to give your baby the expressed milk but avoid bottle feeding if possible. As mastitis is often due to poor latch-on bottle feeding may further complicate the situation because of the associated risk of 'nipple confusion'. Offer your baby your milk using an eye dropper, medicine dropper, feeding syringe or medicine cup. 

If fussiness continues see a breastfeeding counsellor for advice and hands-on assistance to encourage your baby to latch-on and feed effectively. 

Written by Rowena Bennett

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