Pain in the left armpit is mainly due to localized lymphadenitis or sebaceous cyst with infection. Generally speaking, if the sebaceous cyst is infected, anti-inflammatory treatment is usually needed, and then elective surgical excision can be cured after the sebaceous cyst infection symptoms are controlled. Lymphadenitis is divided into two main categories: 1) secondary lymphadenitis caused by inflammation of the chest or upper respiratory tract, usually after anti-inflammatory treatment, the symptoms will be relieved and disappear. 2) axillary lymphadenitis is caused by breast hyperplasia in female patients, which causes secondary lymph node hyperplasia and leads to pain and discomfort in the armpits. Usually, after improving the symptoms of breast hyperplasia, such as oral administration of Easy Pill or Breast Disease Spirit, the symptoms of lymph node hyperplasia and inflammatory hyperplasia in the left armpit can be relieved and disappeared as well.