How is pityriasis caused?

The term pityriasis is actually divided into several types in dermatology, such as pityriasis simplex, pityriasis rosea, and other types of pityriasis, such as pityriasis scalp. Under normal circumstances, the specific cause of pityriasis simplex is not clear, but some are caused by sun exposure or digestive insufficiency or lack of trace elements. Pityriasis rosea is mostly caused by viral infection, an allergic skin disease that occurs in the trunk of the body. Pityriasis scalp is actually a clear feature of seborrheic dermatitis, some of this feature on the performance of a large number of scaly scalp.