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 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. Whether this is due to inflamed and swollen tissue surrounding and closing the duct or thickened milk in the duct is unclear. Jack Newman, a Canadian paediatrician and breastfeeding specialist, says:
A blocked duct is a clog or blockage of milk inside a milk duct that results in a tender or painful lump or firm area in the breast. The skin around the lump may be red and warm. Generally, there is no fever. Sometimes a low fever may occur (usually less than 38.4°C/101°F). Generally, you feel well.
Whatever the cause, inflamed breast tissue or a blockage in a duct could create a thickening or lump which may then press on and narrow other ducts close by—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 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
Anything that prevents good breast drainage could cause a blocked duct e.g. poor positioning and latch (the way baby attaches to the breast), a tight bra or shoulder bag/back pack strap or baby carrier pressing on breast tissue, or even breastfeeding to a schedule instead of on demand. Previous breast surgery, scar tissue, nipple piercing or a blocked nipple pore could also cause blocked ducts.
Preventing a blocked milk duct
Ideas to prevent blocked milk ducts include:
- Check that breast milk can drain freely from all areas of the breast—a baby’s position and latch are important as they can help or hinder this
- Breastfeed at frequent intervals on demand and avoid long periods without feeding or expressing—see How Often Should a Newborn Feed?
- Remember to let your baby finish the first breast first before offering the second side
- Use gentle breast massage and compression on any areas that feel engorged while you breastfeed or use a breast pump.
Signs of a blocked milk duct
Symptoms of a blocked milk may include local pain and tenderness in the breast in the area of the blockage. If close to the surface of the breast, there may be an obvious breast lump due to engorgement. The mother will usually feel well in herself and won’t have a temperature.1 Milk expressed from “blocked areas” may look like strings of spaghetti and mucus 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
- Feed your baby often to try to clear the blockage, at least every two hours. 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 draining the breast thoroughly. If you’re not sure about this contact an IBCLC lactation consultant for help.
- Gentle breast massage before or during breastfeeding/pumping can help release milk. Bear in mind a massage need only involve the same kind of finger tip pressure used when applying a lotion or moisturising cream. Too much pressure or rough handling could cause further damage or inflammation to the breast tissue. Different authors advocate slightly different approaches to the massage technique, see below for a discussion of these.
- Try different breastfeeding positions to help drain 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 have helped some mothers.
- Applying steady pressure or breast compression to the area with the blocked duct (hard lumpy area) during a breastfeed or pumping session can help to release milk.3
- 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.4
- 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.
- 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 trauma in some cases5.
- Rest. It’s important to look after yourself, rest, and remember to eat and drink.
- 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.
- Check with a health professional after 24-48 hours. A blocked or plugged milk duct will usually resolve in 24-48 hours (Newman, 2017) if it is still there for much longer than this, check with your health professional and be vigilant for signs of mastitis.
It can be trial and error to find the best massage technique to use with hand expressing or direct breastfeeding to provide relief for a blocked duct. As mentioned above it is very important to be gentle and not bruise or further inflame the delicate breast tissue by rough handling or vigorous deep massage.6
The Academy of Breastfeeding Medicine mention using an edible oil or nontoxic lubricant on the fingers as a massage oil. They discuss massaging the blocked area first and then moving the massage towards the nipple.7 Others recommend starting the massage close to the nipple and gradually massaging further back towards the blockage until the massage is directly in front of the lump (Walker, 2017).
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 can 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.8 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.9
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.10 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
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 acts as a deep-heating agent that can increase cell activity, reduce pain and increase circulation. The same authors discuss other physical therapy techniques such as kinesiology taping, and the traditional Chinese medicine technique of cupping therapy (Mogensen et al, 2020).
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 duct11 however mechanical gadgets could damage delicate breast tissue and increase bruising or inflammation12.
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 substance which is said to help to prevent blocked ducts in some mothers. Taken as a dietary supplement by the mother, it is thought to help by reducing the constituency (thickness) of breast milk and therefore the tendency for milk to thicken in the ducts. Lawrence and Lawrence also mention rubbing lecithin into the nipple after feeds if there are blocked nipple pores (sometimes called blebs or milk blisters)13 Dr Jack Newman explains more about lecithin and the dosage he recommends:
Lecithin is a food supplement that seems to help prevent blocked ducts. It may do this by decreasing the viscosity (stickiness) of the milk by increasing the percentage of polyunsaturated fatty acids in the milk. It is safe to take, relatively inexpensive, and seems to work in at least some breastfeeding parents. The dose is 1200 mg four times a day.
In contrast Wambach and Spencer 2021 mention 1600mg lecithin daily (p 283) while Dr Hale of Hale’s Medications and Mothers’ Milk [paywall] states that the evidence for lecithin helping with mastitis is lacking as lecithin would be broken down in the stomach and intestines long before being absorbed.
Probiotics and vitamin C
Certain other supplements are mentioned anecdotally as possibly helping the mother who suffers from blocked ducts or mastitis, such as Vitamin C and probiotic supplements1415. 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 16. 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 breast17.
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
- Nipple pain during a breastfeed 18
- Oversupply of breast milk
- Restricting breastfeeds to a schedule instead of on demand
- Using a nipple shield if it affects efficient breast drainage
- 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 or a previous blocked milk duct in the same area making that spot susceptible
- Stress 19, exhaustion or fatigue (Lawrence, 2016)
- A mother who has allergies may be more susceptible to blocked milk ducts.20 And, if a baby has allergies/tummy ache this may increase the chance of blocked ducts or mastitis due to a suboptimal feeding technique.21
- Immunoglobulin A deficiency was linked with blocked ducts in one study.22
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. Inflamed breast tissue or thickened milk in one of the 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.