A plugged (or blocked) duct is an area of the breast where milk flow is obstructed. The nipple pore may be blocked (often called a milk blister) or the obstruction may be further back in the milk ducts. A plugged duct usually comes on gradually and affects only one breast.

Mum 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 mum 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.

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.

A plugged duct can also cause:

• 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 mum 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.
• A plugged duct can be caused by:
• Engorgement or inadequate milk removal (due to latching problems, ineffective suck, tongue-tie or other anatomical variations, nipple pain, sleepy or distracted baby, oversupply, hurried feedings, limiting baby’s time at the breast, nipple shield use, twins or higher order multiples, blocked nipple pore, etc.)
• Infrequent/skipped feedings (due to nipple pain, teething, pacifier overuse, busy mum, return to work, baby suddenly sleeping longer, scheduling, supplementing, abrupt weaning, etc.).
• Pressure on the duct (from fingers, tight bra or clothing, prone sleeping, diaper bag, etc.).
• Inflammation (from injury, bacterial/yeast infection, or allergy).
• Stress anemia, weakened immunity

Common recommendations for plugged duct treatment are heat (with a warm/hot compress), massage, rest, and emptying the breast (by breastfeeding or pumping) and it sometimes requires antibiotics if symptoms are not improving in 12-24 hours, or if mum is acutely ill.Therapearl® 3-in-1 Breast Therapy packs can be used warm/hot directly on the breast before and after nursing as a compress and in between feedings or pumping sessions for pain relief and inflammation.