Milk blisters

Milk blister (Bleb): Causes and mechanism of formation

The milk blister (also known as a bleb) is a small but often very painful white, yellow, or clear spot right at the tip of the nipple. From the outside it may resemble a tiny pimple or bump. This is a common problem among nursing mothers, essentially a microscopic blockage of a milk duct right at its outlet. Although this condition is not dangerous, the sharp, stabbing pain it causes during feeding can cause significant discomfort.

What is a milk blister and how does it form?

The formation of a milk blister is based on a mechanical blockage of one of the many openings of the milk ducts on the surface of the nipple. There are two main mechanisms for this process:

1. Skin overgrowth: The most common cause. A very thin layer of epidermis (skin) grows over the duct opening, forming a “cap” and blocking the milk outlet. Milk that continues to be produced accumulates behind this barrier, forming a small white plug.
2. Blockage by thickened milk: Sometimes a tiny, dense milk particle (a casein clot or calcification) can form inside the duct, getting stuck at the very exit and blocking it.

Connection with other breastfeeding problems

A milk blister rarely occurs on its own. Usually it is a consequence or a precursor of other issues:

• Precursor of lactostasis: A milk blister is the earliest stage of blockage. If it is not removed, milk will continue to accumulate in the duct behind it, leading to a painful plug — blocked milk duct (lactostasis).
• Result of improper latch: An improper or shallow latch can create excessive friction and pressure on the nipple tip, damaging the skin and promoting its overgrowth over the ducts. This is also a cause of sore nipples.
• Result of hyperlactation: With excessive milk supply the pressure in the ducts is higher, which can promote clot formation.

It is important not to try to puncture the blister yourself with a needle, as this can lead to infection and the development of mastitis. There are safer methods that help soften the skin and relieve the blockage.