Long-term clinical studies and observation, believed alopecia the most direct reason that excessive sebum secretion, some component of the skin such as oleic acid, linoleic acid, squalene and other excess have a toxic effect on hair follicles, cause fur poisoning, wither and fall off. Excessive sebum secretion of male hormone such as testicular dihydro ketones, have a toxic effect on hair follicles. Experiments show that will contain these components of oil coating the fur can cause fur a lot off. Seborrheic alopecia directly associated with excessive secretion of sebum is evidence of this: the human sebum secretion and low temperatures, higher temperatures more sebum secretion. Seborrheic alopecia in high temperatures in summer and autumn season is particularly severe, symptoms will be lighter in winter and spring, and even fully.