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. Milk is released through the holes in the nipple (nipple pores). This article looks at the phenomenon of a “blocked milk duct” that is associated with breast inflammation and how to prevent and relieve it.
What is a blocked milk duct?
In the past a blocked (or plugged) milk duct has been described as one through which milk can’t flow due to a blockage of some kind such as a plug or clog of milk leading to local engorgement of milk.1 Newer thinking moves away from the idea of thickened milk blocking a milk duct. Instead it is thought that excess milk in the breast causes inflamed and swollen breast tissue that can surround and close a duct.23 Some authors also hypothesise that ducts can narrow from an overgrowth of pathogenic bacteria in the breast coined “mammary dysbiosis” (ABM, 2022) but others say there is no evidence at all for this theory (Douglas, Vol 18: 1–20 2022).
Whatever the exact cause, if an area of the breast becomes engorged this can press on and narrow other ducts close by—creating a local blockage and slower milk flow from that area of the breast. A useful comparison can be to liken this to a traffic jam; once heavy traffic blocks the main road into the town centre, all roads leading to the town will quickly 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
Blocked milk duct is a type of breast inflammation along with engorgement and mastitis and is caused in the same way. Anything that hinders milk flowing easily from all areas of the breast (ie good breast drainage) could cause breast inflammation e.g. poor positioning (the way baby is held to breastfeed) and latch (the way baby attaches to the breast), a tight bra or shoulder bag/back pack strap pressing on breast tissue, or even breastfeeding to a schedule instead of on demand. Previous breast surgery, scar tissue, a finger pressing into the breast, nipple piercing or a blocked nipple pore could also cause blocked ducts (breast inflammation).
Preventing a blocked milk duct
Ideas to prevent blocked milk ducts include:
- Check that breast milk can flow freely from all areas of the breast—a baby’s position and latch are important as they can help or hinder this. Contact a breastfeeding specialist if breastfeeding is not comfortable and pain free or you have any concerns about positioning and attachment.
- Breastfeed at frequent intervals on demand and avoid long periods without feeding or expressing—see How Often Should a Newborn Feed?
- Let your baby finish the first breast first before offering the second side but do not try to stay on one breast to “reach the hindmilk”
- Check nothing is cutting into the breast such as tight clothing, a finger, poorly fitted bras—including nighttime bras, or whether baby carriers, slings or heavy bags are causing any pressure on the breast.
Signs of a blocked milk duct
Symptoms of a blocked milk duct often include local pain and tenderness in the breast in the engorged area. If close to the surface of the breast, there may be an obvious breast lump due to a build up of milk. The mother will usually feel well in herself and won’t have a temperature unless the breast inflammation has progressed to mastitis.4 Some mothers notice that milk expressed from “blocked areas” may look like strings of spaghetti and mucus may also be present5 and some may observe milk with lumps in it6. Theories for thickened milk are described further in Mastitis Symptoms and Treatment.
How to clear a blocked milk duct
Since engorgement, blocked duct and mastitis are all stages of breast inflammation, management strategies are the same for them all. However not all authors agree on best practice and more research is needed to arrive at a consensus. Most practitioners agree with the following strategies:
- Feed your baby often to keep milk flowing, at least every two hours (Douglas, Vol 18: 1–20 2022; Mitchell et al, 2022). If baby isn’t breastfeeding, hand express or pump frequently instead. If milk won’t seem to flow and the breast is very hard and engorged see Engorgement Relief When Milk Won’t Flow.
- Check your baby is latching deeply (has a big mouthful of breast tissue as well as the nipple in their mouth) and is emptying the breast thoroughly (Douglas, Vol 18: 1–20 2022; Mitchell et al, 2022). A lactating breast is never truly empty so in practice this means removing or draining most of the available milk until you are comfortable again. If you’re not sure about this contact an IBCLC lactation consultant for help.
- Don’t over pump (regularly pump more milk than your baby needs) as this could worsen the engorgement (Mitchell et al, 2022)
- Check whether you have a blocked nipple pore—a bleb or milk blister—on your nipple which is contributing to or causing the blocked milk duct. A bleb may be an inflammatory response to nipple trauma7, see Blisters on Nipples for more information.
- 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 compresses to relieve pain and engorgement.
- Pain relief. There are medications compatible with breastfeeding that can be taken for pain or to help reduce inflammation where needed. The Breastfeeding Network has a fact sheet discussing pain killers and breastfeeding. However, one author notes that over dependence on medications to bring down a fever can interfere with the body’s own mechanisms to down regulate the inflammatory response (Douglas, Vol 18: 1–20 2022).
- Rest. It’s important to look after yourself, rest where possible, and remember to eat and drink.
- Check with a health professional and breastfeeding specialist if there is no improvement in symptoms after 24-48 hours (Newman, 2017), and be vigilant for signs of mastitis.
Strategies over which some practitioners disagree include:
- Trying unusual breastfeeding positions to help clear the blockage. Unusual positions such as kneeling on all fours to feed a baby lying flat on the floor (dangling the breast over the baby), or having the baby’s chin pointing towards the blockage are often suggested to help mothers. Trying different positions may help mothers whose regular feeding position is suboptimal however Mitchell et al say the unusual positions highlighted are not evidence-based and may be unsafe (Mitchell et al, 2022) while Douglas states they could worsen inflammation (Douglas, Vol 18: 1–20 2022).
- Warmth. Some mothers find it helpful to use warm compresses or a heated pad over the blocked milk duct either just before a breastfeed/before pumping or during a breastfeed/pumping session. Lactation consultant and author Marsha Walker mentions combining a warm compress with direct massage over the blocked area during a breastfeed.8 Note that although warmth can provide pain relief it can also widen blood vessels and worsen symptoms (Mitchell et al, 2022; Douglas, Vol 18: 1–20 2022).
- Lecithin. Lecithin is an oily substance which is said to help prevent blocked ducts when taken as a dietary supplement by the mother. It is said to reduce the constituency (thickness) of breast milk and therefore the tendency for milk to thicken in the ducts. However the idea of thickened milk as a cause of blocked ducts has fallen out of favour, and Dr Tom Hale of Hale’s Medications and Mothers’ Milk [paywall] says lecithin would be broken down in the stomach and intestines long before being absorbed. Lawrence and Lawrence mention rubbing lecithin into the nipple after feeds if there are blocked nipple pores (sometimes called blebs or milk blisters)9 If considered, Dr Jack Newman, a Canadian paediatrician and breastfeeding author, discusses a dose of 1200mg four times a day (Newman. 2017) while authors Wambach and Spencer mention 1600mg lecithin daily (Wambach and Spencer, 2021, p 283). See below and Best Breastfeeding Diet and Foods to Avoid for more on diet and inflammation.
- Gentle breast massage before or during breastfeeding/pumping is sometimes advocated to help release milk. While natural breast movement or “breast gymnastics” are generally accepted as helpful, too much pressure or rough handling could cause further damage or inflammation to the breast tissue. Some practitioners advise against massage altogether (Douglas, Vol 18: 1–20 2022). If used, a massage should only involve the same kind of finger tip pressure used when applying a lotion or moisturising cream. Different authors advocate slightly different approaches to massage, see below for a discussion of these and for more information see Engorged Breasts and Nursing Bras FAQ.
- Applying steady pressure or breast compression to the area with the blocked duct (hard lumpy area) during a breastfeed or pumping session may help to release milk (Newman, 2017) but care must be taken not to increase inflammation by vigorous handling of the delicate breast tissue and some practitioners are not in favour of this strategy (Douglas, Vol 18: 1–20 2022).
Not everyone agrees with using breast massage techniques to provide relief for a blocked duct or engorgement (Douglas, Vol 18: 1–20 2022). If used, it is very important to be gentle and not bruise or further inflame breast tissue by rough handling or vigorous deep massage.10 Techniques sometimes suggested include:
Lymphatic breast drainage therapy
The lymphatic system is a waste drainage system for the body. Gentle massage of the lymphatic drainage system in the breast is said to help redistribute excess fluids that are unrelated to milk, moving them towards the lymphatic drainage system via the arm pits (Walker, 2017). This is thought to help relieve severe engorgement or blocked ducts and assist milk to flow. Lactation consultant (and breast surgeon) Katrina Mitchell has developed a handout Lymphatic Massage in Breastfeeding showing how to do this type of massage using very light touch circular movements similar to that used to stroke a cat.
Therapeutic breast massage
This is a type of massage useful for engorged breasts involving a combination of techniques. Lymphatic breast drainage is used to help move fluid towards the armpits alongside alternating massage and hand expression.11 Maya Bolman and Ann Witt of Breastfeeding Medicine of Northeast Ohio discuss therapeutic breast massage in lactation (TBML) in the clip below. A mother can sit up as in the video, or she may find lying on her back to do the massage is more effective.
Wide toothed comb
Using a wide toothed comb to gently stroke/massage the affected breast is sometimes suggested and has helped some mothers. This is thought to improve circulation and reduce congestion similar to the traditional art of gua-sha therapy.12
The following clip from Global Health Media discusses using circular hand movements on the breast from the armpit to the nipple to help clear a blocked duct (watch from 3:00 to 5:00)
Six step recanalization manual therapy (SSRMT)
Zhao et al.13 describe a six step manual therapy for resolving blocked ducts. This involves preparing the breast to widen the ducts and unblock any nipple pores (steps one to four) and then relieving the congestion by manual therapy to expel blocked milk from the ducts (steps five and six). The six steps together are said to take five minutes per breast with the authors reporting good results… out of 3497 women with plugged ducts 98.5% responded positively to the treatment.
- Preparation. Wash hands and have clean towels and a clean collection container available
- Nipple pores. Check the nipples for any blocked nipple pores. Wipe with a dry towel to remove any dried milk or flakes of skin. Stretch the nipple as needed to facilitate the process.
- Nipple manipulation. Hold and lift the nipple to stimulate the let down of milk (milk ejection reflex)
- Push and press the areola from different directions
- Push and knead the breast from the base towards the nipple (milk will spurt from the nipple if this is successful!)
- Check the breast thoroughly section by section for engorged areas (milk stasis).
Further ideas for persistent blocked milk ducts
Ultrasound and other therapies
Mogensen et al discuss the possibility of using ultrasound to treat blocked milk ducts and engorgement and share a suggested ultrasound frequency, intensity and duration of treatment. Therapeutic ultrasound is thought to act as a deep-heating agent that can increase cell activity, reduce pain and increase circulation (Mogensen et al, 2020). However Douglas says there is no evidence to support the use of therapeutic ultrasound for breast inflammation (Douglas, Vol 18: 1–20 2022).
Some mothers have tried to mimic the effects of ultrasound with the vibrations from the flat end of an electric toothbrush held against the blocked duct (Newman, 2017) but mechanical gadgets could damage delicate breast tissue and increase bruising or inflammation14. Mogensen et al also discuss other physical therapy techniques such as kinesiology taping, and the traditional Chinese medicine technique of cupping therapy (Mogensen et al, 2020).
Probiotics and vitamin C
Vitamin C and probiotic supplements are sometimes mentioned as possibly helping the mother who suffers from blocked ducts or mastitis. See Mastitis Symptoms and Treatment and Vitamin C and Breastfeeding for more information.
Recurring blocked milk ducts
Sometimes a mother may find she keeps getting the symptoms of blocked milk ducts or mastitis, no sooner has one episode 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 breast inflammation:
- Poor positioning and/or a shallow latch (with or without sore nipples) leading to poor breast drainage
- Nipple pain during a breastfeed 15
- Oversupply of breast milk
- Restricting breastfeeds to a schedule instead of on demand
- Using a nipple shield if it affects how well milk is removed from the breast
- Using a breastfeeding pillow if it is interfering with good positioning
- Previous breast surgery including breast reduction surgery, breast implants, a biopsy, nipple piercing or any scarring in the breast
- A previous episode of mastitis that hasn’t cleared properly
- Diet. Breast inflammation may be associated with a diet that is high in refined sugars and/or a diet that is very high in omega 6 fatty acids compared with anti-inflammatory omega 3 fatty acids.16
- Stress 17, exhaustion or fatigue (Lawrence, 2016)
- A mother who has allergies may be more susceptible to blocked milk ducts.18 And, if a baby has allergies/tummy ache this may increase the chance of blocked ducts or mastitis due to a suboptimal feeding technique.19
- Immunoglobulin A deficiency was linked with blocked ducts in one study.20
A breastfeeding specialist is the ideal person to help identify causes of recurring mastitis and see the section “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 better after several days of trying the ideas above should be checked with your doctor for a firm diagnosis. If any engorgement is not relieved 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 breast inflammation and prevent it from returning.
Breast milk is carried to the nipple by tiny tubes or milk ducts. Inflamed breast tissue around the ducts could narrow or close them making it difficult for milk to flow freely and create engorgement. Treatment for a blocked milk duct is the same as for mastitis or engorgement; to prioritise milk removal from the breast and keep milk flowing. 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 painful engorgement and mastitis.