Thanks for writing in.
There are a few methods you may try to treat rashes under breast. Rashes are a common skin symptom, especially in moist, dark areas such as under the breast. Most rashes go away within a day or two of using home care
measures, although some rashes persist, depending on the cause. Fortunately, most rashes under your breast that occur after sweating during exercise are treatable and preventable with proper self-care measures
1. Baby powder
2. Medicated body powder.
4. Antifungal cream.
Try to keep the area dry and prevent excessive sweat formation.
Hope this helps