Pitryiasis rosea is allergy developed after viral infection. Generally It occurs after episode of fever or illness.If u have itching u have to take medications for it otherwise it generally resolves on its own.

Pityriasis rosea is a self limiting condition which is usually present for 6 to 8 weeks. Causes include viral infections like herpes and drugs like barbiturates, gold, retinoids and terbinafine can precipitate P.rosea. As already mentioned it is a self limiting condition, lesions resolve without treatment. If itching is severe, topical calamine lotion can be used. If lesions are extensive then a topical steroid can be used. P.rosea rarely recurs, but if persists or recurs the patient should be evaluated.