Plugged Ducts and Mastitis

By Kelly Bonyata, BS, IBCLC

How do I know if I have a plugged duct or mastitis?

A plugged (or blocked) duct is an area of the breast where milk flow is obstructed. The nipple pore may be blocked (see Milk Blister), or the obstruction may be further back in the ductal system. A plugged duct usually comes on gradually and affects only one breast.
Local symptoms
Mom will usually notice a hard lump or wedge-shaped area of engorgement in the vicinity of the plug that may feel tender, hot, swollen or look reddened. Occasionally mom will only notice localized tenderness or pain, without an obvious lump or area of engorgement. The location of the plug may shift.A plugged duct will typically feel more painful before a feeding and less tender afterward, and the plugged area will usually feel less lumpy or smaller after nursing. Nursing on the affected side may be painful, particularly at letdown.
Systemic symptoms
There are usually no systemic symptoms for a plugged duct, but a low fever (less than 101.3°F / 38.5°C) may be present.
Per Maureen Minchin (Breastfeeding Matters, Chapter 6), mastitis is an inflammation of the breast that can be caused by obstruction, infection and/or allergy. The incidence of postpartum mastitis in Western women is 20%; mastitis is not nearly so common in countries where breastfeeding is the norm and frequent breastfeeding is typical. Mastitis is most common in the first 2-3 weeks, but can occur at any stage of lactation. Mastitis may come on abruptly, and usually affects only one breast.
Local symptoms
Local symptoms are the same as for a plugged duct, but the pain/heat/swelling is usually more intense. There may be red streaks extending outward from the affected area.
Systemic symptoms
Typical mastitis symptoms include a fever of 101.3°F (38.5°C) or greater, chills, flu-like aching, malaise and systemic illness.

Common (and not-so-common) side effects of plugged ducts or mastitis

Plugged duct

  • Milk supply and pumping output from the affected breast may decrease temporarily. This is normal and extra nursing/pumping generally get things back to normal within a short time.
  • Occasionally a mom may express “strings” or grains of thickened milk or fatty-looking milk.
  • After a plugged duct or mastitis has resolved, it is common for the area to remain reddened or have a bruised feeling for a week or so afterwards.


Side effects may be the same as for a plugged duct, plus:

  • Expressed milk may look lumpy, clumpy, “gelatin-like” or stringy. This milk is fine for baby, but some moms prefer to strain the “lumps” out.
  • Milk may take on a saltier taste due to increased sodium and chloride content – some babies may resist/refuse the breast due to this temporary change.
  • Milk may occasionally contain mucus, pus or blood.

What are the usual causes of plugged ducts or mastitis?

Plugged duct Mastitis

Milk stasis / restricted milk flow

… may be due to:

Stress, fatigue, anemia, weakened immunity

Milk stasis (usually primary cause)

  • Same as for blocked duct.
  • Blocked duct is also a risk factor.


  • Sore, cracked or bleeding nipples can offer a point of entry for infection.
  • Hospital stay increases mom’s exposure to infectious organisms.
  • Obvious infection on the nipple (crack/fissure with pus, pain) is a risk factor.
  • Past history of mastitis is a risk factor.

Stress, fatigue, anemia, weakened immunity

What is the usual treatment for plugged ducts and mastitis?

It’s always best to treat a plug immediately and aggressively to avoid escalating into mastitis.

CAUTION: Do NOT decrease or stop nursingwhen you have a plugged duct or mastitis,as this increases risk of complications (including abscess).
Plugged Duct

  • Rest
  • Adequate fluids
  • Nutritious foods will help to strengthen mom’s immune system

  • Bed rest (preferably with baby)
  • Increase fluids, adequate nutrition
  • Get help around the house
BREASTFEEDING MANAGEMENT — SAME for plugged duct or mastitis
— important to start treatment promptly 
“Heat, Massage, Rest, Empty Breast”
  • Nurse frequently & empty the breasts thoroughly.Aim for nursing at least every 2 hrs. Keep the affected breast as empty as possible, but don’t neglect the other breast.
  • When unable to breastfeed, mom should express milk frequently and thoroughly (with a breast pump or by hand).
Before nursing
  • Use heat & gentle massage before nursing- Warm compress. Try using a disposable diaper: fill the diaper with hot water (try the temperature on your wrist first to avoid burns), squeeze the diaper out a bit, then put the inside of the diaper toward the breast. This will stay warm much longer than a wet cloth.- Basin soak. Fill sink or bowl with hot water and submerge breast in water while massaging the plugged area toward the nipple. Some report better results when epsom salts are added to the water — add a handful of epsom salts per 2 quarts (2 liters) of water. Rinse with fresh water before nursing, as baby may object to the taste.- Hot Shower. It can be helpful to massage in the shower with a large-toothed comb. The comb should be drawn through a bar of soap until it is very soapy and then used to gently massage over the affected area in the direction of the nipple.
  • Loosen bra & any constrictive clothing to aid milk flow.
  • Massage will help to improve milk drainage and improve symptoms. See Breastfeeding Medicine of Northeast Ohio’s video for a demonstration of the basics of therapeutic breast massage.
While nursing
  • Nurse on the affected breast first; if it hurts too much to do this, switch to the affected breast directly after let-down.
  • Ensure good positioning & latch. Use whatever positioning is most comfortable and/or allows the plugged area to be massaged.Note: Advice to point baby’s chin (or nose) toward the plugged area is not necessarily going to be helpful as it is based on the idea that the milk ducts take a nice, direct route to the nipple – recent research tells us that this is not true, and that a particular duct might begin in one area of the breast but can “wander” in many different directions before terminating in any area of the nipple.
  • Use breast compressions.
  • Massage gently but firmly from the plugged area toward the nipple.
  • Try nursing while leaning over baby (sometimes called “dangle feeding“) so that gravity aids in dislodging the plug.
After nursing
  • Pump or hand express after nursing to aid milk drainage and speed healing.
  • Use cold compresses between feedings for pain & inflammation.
Plugged duct Mastitis


  • Pain reliever/anti-inflammatory(e.g., ibuprofen)
  • Second choice – pain reliever alone(e.g.,acetaminophen)


  • Same as for plugged duct


  • No


  • No: If symptoms are mild and have been present for less than 24 hours.
  • Yes: If symptoms are not improving in 12-24 hours, or if mom is acutely ill.
  • Most common pathogen is penicillin-resistant Staphylococcus aureus.
  • Typical antibiotics used for mastitis:- Dicloxacillin, flucloxacillin, cloxacillin, amoxycillin-clavulinic acid- Cephalexin, erythromycin, clindamycin, ciprofloxacin, nafcillin
  • Most recommend 10-14 day treatment to prevent relapse. Do not discontinue treatment earlier than prescribed.
  • Consider probiotic to reduce thrush risk.
  • Several studies have shown that probiotic supplements (certain Lactobacillus strains) are effective in treating infectious mastitis and also resulted in a lower occurrence of repeat mastitis.
  • Some mothers also use natural treatments.
* Consult your health care provider for guidance in your specific situation. The medication information is taken from the references listed below and is provided for educational purposes only.

Does mastitis always require antibiotics?

No, mastitis does not always require antibiotics.

Mastitis is an inflammation of the breast that is most commonly caused by milk stasis (obstruction of milk flow) rather than infection. Non-infectious mastitis can usually be resolved without the use of antibiotics. However, per the World Health Organization document Mastitis: Causes and Management, “Without effective removal of milk, non-infectious mastitis was likely to progress to infectious mastitis, and infectious mastitis to the formation of an abscess.”

Per the Academy of Breastfeeding Medicine’s Clinical Protocol for Mastitis:

“If symptoms of mastitis are mild and have been present for less than 24 hours, conservative management (effective milk removal and supportive measures) may be sufficient. If symptoms are not improving within 12-24 hours or if the woman is acutely ill, antibiotics should be started.”

If a mom with mastitis has no obvious risk factors for infection (as noted in the box below), it is likely that the mastitis is non-infectious and, if properly treated, will resolve without antibiotics.

When you have mastitis…

Talk to your DR about starting

antibiotics immediately if:

  • Mastitis is in both breasts.
  • Baby is less than 2 weeks old, oryou have recently been in the hospital.
  • You have broken skin on the nipplewith obvious signs of infection.
  • Blood/pus is present in milk.
  • Red streaking is present.
  • Your temperature increases suddenly.
  • Symptoms are sudden and severe.


  • Re-evaluate treatment plan if symptoms do not begin to resolve within 2-3 days.
  • Investigate further if mom has more than 2-3 recurrences in the same location.
  • Consider the possibility of thrush if sore nipples begin after antibiotic treatment.

As always, consult your own health care provider to determine how this information applies to your specific circumstances.


References and additional information


@ other websites

Amir LH. Mastitis: Are we overprescribing Antibiotics? Current Therapeutics 2000 (April); 41:24-28.

Amir LH. Management of Mastitis. Current Therapeutics 2000 (April); 41:29.

Fetherston C. Mastitis in lactating women: physiology or pathology? Breastfeed Rev 2001 Mar;9(1):5-12.

Fetherston C. Risk factors for lactation mastitis. J Hum Lact 1998 Jun;14(2):101-9.

Foxman B, D’Arcy H, Gillespie B, Bobo JK, Schwartz K. Lactation mastitis: occurrence and medical management among 946 breastfeeding women in the United States. Am J Epidemiol. 2002 Jan 15;155(2):103-14.

Kinlay JR, O’Connell DL, Kinlay S. Risk factors for mastitis in breastfeeding women: results of a prospective cohort study. Aust N Z J Public Health. 2001 Apr;25(2):115-20.

Lawrence R, Lawrence R. Breastfeeding: A Guide for the Medical Profession, 6th ed. Philadelphia, Pennsylvania: Mosby, 2005, p. 299-301, 562-570, 1068-1071.

Livingstone VH, Willis CE, Berkowitz J. Staphylococcus aureus and sore nipples. Can Fam Physician. 1996 Apr;42:654-9.

Mohrbacher N, Stock J. The Breastfeeding Answer Book, Third Revised Ed. Schaumburg, Illinois: La Leche League International, 2003, p. 496-507.

Prentice A, Prentice AM, Lamb WH. Mastitis in rural Gambian mothers and the protection of the breast by milk antimicrobial factors. Trans R Soc Trop Med Hyg. 1985;79(1):90-5.

Riordan J. Breastfeeding and Human Lactation, 3rd ed. Boston and London: Jones and Bartlett, 2005, p. 248-253.

Riordan JM, Nichols FH. A descriptive study of lactation mastitis in long-term breastfeeding women. J Hum Lact. 1990 Jun;6(2):53-8.

Smith A, Heads J. Breast Pathology. In: Walker M, ed. Core Curriculum for Lactation Consultant Practice. Boston: Jones and Bartlett, 2002, p. 180-190.

Walker M. Breastfeeding Management for the Clinician: Using the Evidence. Boston: Jones and Bartlett, 2006, p. 388-394.

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