Diseases and Conditions
Pityriasis rosea
Overview
Symptoms
Causes
Complications
Diagnosis
Treatment
Lifestyle and home remedies
Preparing for an appointment
Causes
The exact cause of pityriasis rosea is unclear. Some evidence indicates the rash may be triggered by a viral infection, particularly by certain strains of the herpes virus. But it's not related to the herpes virus that causes cold sores. Pityriasis rosea isn't believed to be contagious.