Breast milk is made and stored in small milk producing sacs (alveoli) in the breast and delivered to the nipple via little tubes (milk ducts). When a baby begins to breastfeed, release of the hormone oxytocin triggers the let down reflex which causes the cells around the alveoli to contract forcing breast milk into the milk ducts towards the nipple. This article looks at why milk ducts might become blocked, and how to prevent and treat them if they do.
What is a blocked milk duct?
As the name suggests, a blocked (or plugged) milk duct is one through which milk can’t flow due to a blockage of some kind in the tiny tube. Jack Newman, a Canadian paediatrician and breastfeeding specialist, explains how thickened milk is the cause of the blockage or plug in the duct:
An abundant milk supply plus a baby who doesn’t latch well result in partial “emptying” of the breast. (Of course, a breast is never “empty” since the milk is being made continuously, but in this situation the baby leaves more milk in the breast than might be desirable.) That leftover milk can sit in the breast and thicken, blocking the duct.
A blockage in one duct will create a thickening or lump which may then press on other ducts close by which can narrow or close them too—creating a bigger blockage and slower milk flow for your baby. A useful comparison can be to liken this to a traffic jam; once heavy traffic blocks a town centre, all roads leading to the town will be affected. Once milk is not flowing in one area of the breast it can quickly become uncomfortably engorged and affect a wider area, and, if this is not relieved, it could develop into mastitis.
Causes of a blocked milk duct
Anything that prevents good breast drainage could cause a blocked duct e.g. poor positioning, a shallow latch, a tight bra pressing on the glandular tissue, or even breastfeeding to a schedule instead of on demand. Previous breast surgery or any scarring, nipple piercing or a blocked nipple pore could also cause blocked ducts.
Preventing a blocked milk duct
In order to prevent blocked milk ducts try to make sure your baby’s position and latch (the way your baby attaches to the breast with a wide mouth) are as good as possible. This will help breast milk drainage from all areas of the breast. Remember to let your baby finish the first breast first before offering the second and use gentle breast massage and compression on any areas that feel engorged while you breastfeed/use a breast pump.
Signs of a blocked milk duct
Caught early, a blocked milk duct usually causes local pain in the breast in the area of the blockage. There may also be an obvious breast lump or a larger area of the breast with painful engorgement. The mother will usually feel well in herself and won’t have a temperature. Milk expressed from “blocked areas” may look like strings of spaghetti 1, and mucous may also be present 2. It can sometimes be very difficult to distinguish a blocked duct from mastitis because they may be present together, but the treatment for both conditions are similar.
How to clear a blocked milk duct
Treatment for a blocked milk duct is very similar to ideas for treatment for mastitis—apart from the use of cabbage leaves which Dr Jack Newman says shouldn’t be used for a blocked milk duct (Newman, 2014, p160):
- Feed your baby often to try to clear the blockage.
- Check your baby is latching deeply and draining the breast thoroughly. If you’re not sure about this contact your IBCLC lactation consultant for help.
- Use gentle breast massage or breast compression to put gentle pressure on the blocked milk duct or any other hard lumpy areas while baby suckles. Massaging gently above the blocked duct followed by massage and hand expression behind the nipple may be helpful. For a video of therapeutic breast massage in lactation see Engorged Breasts or Engorgement Relief When Milk Won’t Flow. You could also try massaging the breasts while pumping. Using a wide toothed comb to gently stroke the affected breast has helped some mothers.
- Try different breastfeeding positions to help drain the blockage. Unusual positions such as kneeling on all fours to feed baby lying flat on the floor (dangling the breast over the baby), or having the baby’s chin pointing towards the blockage have helped some mothers.
- Warmth? Some mothers find it helpful to use warm compresses or a heated pad on the blocked milk duct prior to a breastfeed or before hand expressing.
- Cold therapy. If there is a lot of accompanying engorgement, heat can bring more swelling to the area whereas cold therapy between breastfeeds, can reduce pain, swelling and inflammation. See Engorged Breasts for more information about using cold for engorgement.
- Check whether you have a blocked nipple pore—a bleb or milk blister—on your nipple which is contributing to the blocked milk duct. A bleb may be an inflammatory response to nipple trauma in some cases3.
- Take anti-inflammatory medication for pain and to reduce inflammation.
- Try to look after yourself, rest, and remember to eat and drink.
A blocked or plugged milk duct will usually resolve in 24-48 hours (Newman, 2014) if it is still there for much longer than this, check with your health professional and be vigilant for signs of mastitis.
Ideas for treating stubborn blocked milk ducts
Jack Newman discusses the possibility of trying ultrasound to treat blocked milk ducts and the dose needed in his 2017 article Blocked Ducts and Mastitis. He shares that some mothers have tried, with some success, to mimic the effects of ultrasound with the vibrations from the flat end of an electric toothbrush held against the blocked duct.
Check for tight clothing
Check nothing is cutting into the breast such as tight clothing, poorly fitted bras—including nighttime bras, or whether baby carriers, slings or heavy bags are causing any pressure on the breast.
Lecithin is an oily food supplement which may help to prevent blocked ducts in some mothers. It is thought to help by reducing the constituency (thickness) of breast milk and therefore the tendency for milk to thicken in the ducts. Dr Jack Newman explains more about lecithin and the dosage he recommends:
Lecithin refers to a group of phospholipids that are found in many foods, including egg yolk and soybeans; it is sold as a food supplement in pharmacies and health food stores. It may help to prevent recurrent blocked ducts. We usually recommend 1,200 mg three or four times a day, but some mothers take twice this amount. It comes in capsule form and also as a liquid. We usually recommend the capsule form, since it is easier to swallow.
However Dr Hale of Hale’s Medications and Mothers’ Milk [paywall] states that the evidence for lecithin helping with mastitis is lacking.
Certain other supplements are mentioned anecdotally as possibly helping the mother who suffers from blocked ducts or mastitis, such as Vitamin C and probiotic supplements 4 (see Mastitis Symptoms and Treatment for more information).
Problematic or recurring blocked ducts may be associated with a diet that is rich in saturated fats. Eating more polyunsaturated fatty acids as well as adding lecithin (above) to the mother’s diet may be helpful 5. A healthy balance of essential fatty acids in the diet is important. It is thought that a diet that is very high in omega 6 fatty acids compared with anti-inflammatory omega 3 fatty acids may help to cause inflammation in the body and could be associated with mastitis in the breast6.
Recurring blocked milk ducts
Sometimes a mother may find she keeps getting blocked milk ducts, no sooner has one cleared than another takes its place. As with recurring mastitis, there are a number of risk factors to be aware of that can increase your chances of recurring blocked ducts:
- Poor positioning and/or a shallow latch (with or without sore nipples) leading to poor breast drainage
- Restricting breastfeeds to a schedule instead of on demand
- Using a nipple shield
- Using a breastfeeding pillow if it is interfering with good positioning
- Previous breast surgery (breast reduction surgery, breast implants, biopsy), nipple piercing or any scarring in the breast
- A previous episode of mastitis that hasn’t cleared properly or a previous blocked milk duct in the same area making that spot susceptible
- Being very stressed or anaemic 7
- Thrush can be associated with blocked milk ducts (Newman, 2014; Bonyata, 2018)
- Vigorous exercise particularly when using the upper arms and chest 8.
- A mother who has allergies may occasionally be more susceptible to blocked milk ducts (Bonyata, 2018).
See the section “Treatment for recurrent mastitis” in Mastitis Symptoms and Treatment for further discussion of treatment ideas.
If your blocked milk duct is still there…
A blocked milk duct that isn’t getting smaller after several days of trying the ideas above should be checked with your doctor for a firm diagnosis. If the blockage is causing any engorgement this could lead to mastitis or even to an abscess if left unchecked. Some breast lumps might not be blocked milk ducts after all e.g. a galactoceole is a milk cyst—your doctor can help with a diagnosis. Most medical tests for diagnosis are compatible with breastfeeding. Work with your doctor and IBCLC lactation consultant to help solve your blocked milk duct and prevent it from returning.
Breast milk is carried to the nipple by tiny tubes or milk ducts. Any thickened milk in one of these tubes can create a blocked milk duct through which milk is unable to flow freely. Treatment for a blocked milk duct is very similar to that needed for mastitis; to increase breast drainage and promote milk flow. If a blocked milk duct isn’t cleared promptly within a few days check with your health care professional for a firm diagnosis. A blocked duct could lead to unrelieved engorgement and mastitis.