May also be called: "Christmas Tree" Rash
Pityriasis rosea (pit-uh-RYE-uh-sis ROW-zee-uh) is a harmless skin rash that is common in older kids and young adults.
Pityriasis rosea usually starts with one large, slightly raised patch of scaly skin on the chest, belly, back, or thighs. As the rash spreads, the original patch (called a herald patch or "mother" patch) is joined by a number of smaller spots that spread out across the torso.
In some cases, the spots spread to the arms and legs. These spots are sometimes called "daughter" patches. They're generally oval and often form a pattern on the back that resembles a Christmas tree. Both the "mother" and "daughter" patches can be itchy and scaly, and the rash may sometimes be accompanied by flu-like symptoms.
Doctors aren't sure what causes pityriasis rosea, but it's not due to allergies, bacteria, or fungi. Most cases of pityriasis rosea go away in 1 to 2 months without any treatment.
When pityriasis rosea does require treatment, it's usually just to control the itching. Over-the-counter itch creams, allergy syrups, oral antihistamines, and even just getting a moderate amount of sunlight can help control itching and treat the rash. However, hot baths and showers and getting overheated can make the itching worse.
Pityriasis rosea is harmless and is not contagious, and usually goes away on its own. Still, it's important to get it checked out by a doctor to rule out other conditions.
All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.
