The yellowish liquid from the breasts may be caused by breast hyperplasia, acute mastitis, or breast cancer. 1. Mammal hyperplasia: Mammal hyperplasia is more common in women of childbearing age between 30 and 50 years old, and is considered to be caused by hormonal disorders in the body. Clinical symptoms will show nodular changes of breast hyperplasia, which may be accompanied by breast swelling and pain, as well as the secretion of yellow fluid in the nipple. 2. Acute mastitis: Acute mastitis is an acute purulent infection of the breast tissue. When the scope of infection increases and a breast abscess forms, a large amount of yellow pus may be discharged when the nipple is squeezed, which may be accompanied by breast pain and other symptoms. 3. Breast cancer: Some breast cancer patients may also have the phenomenon of pushing out pus, pulp and milk from the nipple. Consider the lesion tissue damage to the mucous membrane cells triggered. The yellow fluid coming out of the breast is not entirely caused by the above factors, and the patient needs to go to the hospital for a breast examination to deal with the cause of the disease.