A milk blister – also called a "bleb" or "nipple blister" -- can develop even if you are not breastfeeding. As long as your breasts contain milk, a milk blister can develop. Milk blisters can be painful and upsetting, especially if symptoms last for a long period.
A milk blister can appear as an irregularly shaped, flat cyst on the nipple. It will stay flat against the skin even when you apply pressure to your nipple area. It can appear yellow, white or clear. Even though they are typically painless, you may experience pain when you squeeze or touch the blisters. As the blister heals, the skin may peel and form crust around the cyst. Milk blisters can linger for several weeks.
A milk blister can develop if a pore in your nipple around the milk duct becomes clogged with nipple tissue or a bit of breast milk. The milk behind this blister backs up, resulting in redness, inflammation and pain. Milk blisters can develop any time, especially if you attempt to breastfeed and stop due to problems with your baby latching on properly.
Hold a warm compress like a hot, wet cloth onto the milk blister for several minutes. Rub the skin gently with the cloth to exfoliate the skin over the blister and dislodge the blockage. If that doesn't work, wash your hands and gently pull at the blockage with your fingernails. Apply a lotion to the blister to keep it moist and ease pain. A doctor can lance the milk blister with a sterile needle.
If your milk blister appears brown or reddish, Breastfeeding.com notes that is it likely a blood blister. A blood blister can also be due to an attempt at breast-feeding, especially if your baby had an improper latch. A white spot can also be just a hardened clump of fatty milk, which can also plug your nipple. However, the white tip will be exposed and not concealed by any skin.