Heat and sweat can cause a rash known as prickly heat, or miliaria, to crop up. The tiny clear or red bumps cause itching and what many people describe as a prickling sensation. Miliaria usually appears where two skin surfaces rub together, such as beneath the breasts.
To prevent the rash, after bathing, gently pat the area between skin folds dry. Also avoid wearing tight clothing and synthetic fibers; opt for cotton, linen, and other natural fibers that allow moisture to evaporate more readily. Try to expose already irritated areas to air whenever possible. If the rash is bad, talk to your doctor about using a medicated preparation, such as a 1-percent hydrocortisone cream.