Underarm lymph nodes are enlarged lymph nodes. There are many reasons for women to have enlarged lymph nodes in their armpits, generally considered to be caused by infectious factors, breast diseases, tumors and other reasons. 1. Infectious factors: the lymphatic system is the body’s immune system, when infected by bacteria, viruses and other pathogenic microorganisms, lymph nodes will be enlarged. For example, if you suffer from folliculitis, pneumonia, etc., it may be accompanied by the clinical symptoms and manifestations of the corresponding diseases. 2. Breast diseases: for example, when women suffer from breast hyperplasia or mastitis, there will be localized lymph node enlargement, and at the same time, there will be breast swelling and pain or breast lumps, and so on. 3. Tumor: For example, when women suffer from breast cancer, lung cancer, stomach cancer, liver cancer and other tumors, the lymph nodes in the armpit may be enlarged due to invasion, and may be accompanied by anemia, emaciation, loss of appetite and other manifestations. It is necessary to go to the hospital and let the doctor make a clear diagnosis after a detailed examination, and you can’t use medicines randomly by yourself.