Pityriasis rosea is a common skin disease that occurs in adolescents and is prone to develop in spring and fall. Clinical features are multiple erythematous scaly rashes on the trunk and proximal extremities, with oval-shaped rashes and a long axis consistent with (parallel to) skin lines. Since many patients have a history of upper respiratory tract infection prior to the onset of the disease, it is presumed that the disease may be associated with viral or mycoplasma infections. Initially, the rash is a few millimeters in size, a pale red macule or papule, which gradually expands to an oval or ring-shaped lesion of 1-2 cm. The boundaries are relatively clear, and the periphery is surrounded by collar-like fine bran-like scales. The rash is often multiple, symmetrically distributed on the trunk and proximal extremities, and may be absent or mildly pruritic. The lesions gradually increase and expand within 1-3 weeks, and then begin to resolve on their own, usually for several months. Irradiation UVB can shorten the course of disease obviously. Patients with pityriasis rosea should pay attention to avoid cold and flu again as much as possible, so as to avoid prolonging the course of the disease and prolonging it.