Medically reviewed by Susan Bard, MDMedically reviewed by Susan Bard, MD Buttock rashes can develop from heat, allergies ...

You're most likely to find heat rash in places where you experience excessive sweating and skin-on-skin friction — like the neck, armpits, buttocks, or waistline. That's because it can be ...

sometimes accompanied by muscle aches in the buttocks. The rash itself may include painful, fluid-filled blisters. Heat rash, or miliaria, develops when your sweat glands and ducts become clogged.