Pityriasis rosea (say "pih-tih-RY-uh-sus ROH-zee-uh) is a common skin problem that causes a rash. The rash often begins with a herald patch—a single, round-to-oval, and pinkish, purple, or red-brown patch that is scaly with a raised border. Days or weeks later, more small patches often appear on the belly, chest, back, arms, and legs. Patches sometimes spread to the neck or face.

Pityriasis rosea is usually harmless.