The causes of pain under the right armpit of women mainly include the following aspects: 1. Consider that it is caused by axillary lobe and breast lobule hyperplasia, the right armpit of women is distributed under the axillary lobe of the right breast tissue, the body due to irregular life or work, life pressure, will lead to the body estrogen secretion disorder, and then stimulate the breast lobules, including axillary lobe hyperplasia, causing pain; 2. Lymphadenitis is caused by the distribution of lymph nodes under the armpit, and local lymph node inflammation can cause armpit pain; 3. It is considered to be caused by muscle strain in the armpit caused by lifting the upper limbs or strenuous activities, which in turn causes pain in the armpit; 4. It is considered to be caused by soft tissue infection and swelling in the armpit, such as sebaceous gland cysts and other infections. There are many causes of armpit pain in women, so you need to visit a hospital for surgery and have a blood test and an ultrasound examination of the armpit to clarify.