The pain in the right side of the front chest under the breast may be breast disease, heart disease, intercostal neuralgia, etc., and you should consult a doctor in time to find out the cause of the disease. 1. Breast disease: pain under the breast may be caused by menstrual pain, mastitis, breast tumor and so on. Before and after menstruation, the hormone level in the body is in an unstable state, which will cause local stimulation and trigger pain; mastitis can be manifested as red and swollen skin, elevated skin temperature, breast pain, etc.; some breast tumors can also be manifested as breast pain. 2. Heart disease: pain under the breast on the right side of the front chest, there may be a hidden pain under the chest, this situation is likely to be caused by heart disease, mainly including myocardial ischemia, angina pectoris, heart attack and so on. 3. Intercostal neuralgia: Intercostal neuralgia can also lead to significant pain in the right side of the chest under the breast. The pain in the lower part of the right breast can also be caused by other factors, such as trauma, skin rashes, etc. It is recommended to consult a doctor as soon as possible to clarify the cause of the disease, and follow the doctor’s instructions to receive treatment.