Pityriasis rosea is a common skin problem that causes a pink- or salmon-colored rash on the body. Although it can occur at any age, it is seen most often in people age 10-35. Pityriasis rosea is usually harmless. But it can cause serious problems in pregnant women. The cause of pityriasis rosea is unknown. Follow the links below to find WebMD's comprehensive coverage about pityriasis rosea, including what it looks like, how to treat it, and much more.