Exercise Sweating Leading to a Rash Under Breasts

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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 and changes to your workout habits.

Environmental Causes

Exercising in hot weather often leads to a skin rashes, especially on parts of your body that are covered with clothing and where sweat is not able to evaporate. If your workout clothes are new, chemicals used in their manufacturing irritate the sensitive skin under your breasts, leading to a rash. A sports bra that is too tight produces friction against your skin while you exercise, producing a rash where the bra rubbed against your skin. Use of a new detergent or skin care product is another cause of rashes on your skin.

Medical Causes

Skin conditions such as eczema, dermatitis, and hives from allergic reactions are common causes of skin rashes. If you work out regularly and wear tight fitting clothing made of polyester, spandex or other man-made materials, sweat that accumulates under your breasts promotes the growth of yeast on your skin, resulting in candidiasis. Although most rashes around your breast result from the same causes as rashes on the rest of your body, certain breast diseases also cause rashes, usually just on one breast. A breast abscess or mastitis, common among lactating women, causes a red, streaked rash on your skin. Other serious breast diseases including inflammatory breast cancer, mammary duct ectasia and Paget’s disease of the breast also cause rashes.


Take a warm shower after you exercise, taking care to gently cleanse the area under your breasts. Avoid hot water and rough scrubbing, as these can further irritate your skin, worsening the rash and making it itch. Apply hydrocortisone cream to your skin if your rash itches. If the rash on your breast does not go away within a few days of performing self care treatments, see your doctor. Your doctor will perform a breast exam and, if necessary, conduct imaging studies such as x-ray or magnetic resonance imaging (MRI) to determine a course of medical treatment for your rash.


Washing new workout clothes helps remove any chemical additives that could irritate your skin. Using free and clear detergents on your clothing and vinegar in your washing machine as a fabric softener rather than chemical fabric softener sheets also helps prevent skin irritations from fabric. Wear properly fitting bras to avoid friction against your skin. After working out, showering and thoroughly drying off helps remove sweat and moisture from your skin, reducing the risk of some skin rashes. Exercising indoors on hot days or early in the morning before the heat builds up helps prevent heat-related skin rashes.