An area of the skin that has changes in texture or color and may look inflamed or irritated. The skin may be red, warm, scaly, bumpy, dry, itchy, swollen, or painful. It may also crack or blister. A rash can occur in one area of the body or all over the body and may look very different depending on the cause. It may be a sign of a specific medical condition or a side effect of a medicine or treatment. Some causes of skin rashes include allergies, infection, heat, and immune system disorders.