<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have an itchy sensation starting from the right side of my left breast spanning across my chest underneath my right breast. first starting feeling itchy about a week ago. At first it was red and looked like a rash, now the rash is barely noticeable but still itchy. any thoughts as to what thi sis?  <response>: Hi, I have read your query understood your concern. The itchy rash under breast is common in fat, diabetic,pendulous large breasts. In such conditions, there is a lot of sweating, the moistness helps breeding of bacteria fungi, thus a skin infection develops itching increases. Simple sweating can produce prickly heat rash Cleanlinesscoolness talcum powder help. Fungus infection needs to be diagnosed by skin specialists treatment accordingly. Allergy to material of under garments-stop use of the allergen use cotton garments. Bacterial rash has pus filled tubercles-need antibiotic. Please consult a skin specialist for diagnosis advice. Thanks 