Skin rashes can be caused by a number of contributing factors. These can include allergens, infections, heat, immune system disorders, and medications. They can cause extreme discomfort and irritation. One of the most common skin disorders is known as atopic dermatitis or eczema. Your doctor may ask you to avoid using harsh chemicals, soaps, and detergents. You may be required to apply a particular lotion, medicated cream or ointment to lessen the severity of the symptoms.