How did the rash start?

Rash belongs to a kind of skin lesion, causing rash to show the disease and rash, the incidence of a variety of types, need to be analyzed according to different circumstances is caused by what causes. 1. macula: macula is generally caused by viral infection, physical factors, allergic diseases, autoimmune diseases, congenital genetic diseases and metabolic and nutritional disorders. 2. urticaria: mostly by allergies, infections, cold, sunlight and other stimuli, mental and genetic factors.