A white blister on the breastfeeding nipple may be caused by cracked nipple, papillitis, folliculitis and other diseases. 1. Cracked nipple: cracked nipple is caused by the destruction of skin integrity, is a common disease during breastfeeding, there are nipple breakage, dryness or bleeding and other manifestations, serious cases can appear blisters, and then manifested as a white bubble on the breastfeeding nipple. 2. Nipple inflammation: patients often have one or both sides of the nipple redness, swelling, cracking, pain, and even pus blisters, which is manifested as a breastfeeding nipple with a white bubble, mostly due to the baby’s sucking and salivary impregnation, the maternal resistance is low, the baby contains the nipple in the wrong position as well as not cleaning the nipple and so on will also induce nipple inflammation. 3. Folliculitis: Folliculitis is a red papule centered on a hair follicle with a white pustule on top, which is mainly an inflammatory reaction triggered by bacterial infection, and the patient may have the symptom of a white bubble on the breastfeeding nipple. There are many causes of a white blister on the breastfeeding nipple, and it is recommended that patients go to the hospital in time to clarify the cause of the disease.