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Topic Overview

What is pityriasis rosea?

Pityriasis rosea (say "pih-tih-RY-uh-sus ROH-zee-uh") is a common skin problem that causes a rash. Although it can occur at any age, it is seen most often in those between the ages of 10 and 35.

Pityriasis rosea is usually harmless.

What causes pityriasis rosea?

Experts aren't sure what causes pityriasis rosea. Unlike many other skin conditions, it is not an allergic reaction or caused by a fungus or bacteria. It may be caused by a virus.

The rash does not appear to spread from person to person.

What are the symptoms?

Pityriasis rosea causes a rash.

  • The rash often begins with a single, round or oval, pink patch that is scaly with a raised border (herald patch). The size of the patch ranges from 2 cm (0.8 in.) to 10 cm (3.9 in.). The larger patches are more common. See a picture of a herald patch .
  • Days to weeks later, salmon-colored, 1 cm (0.4 in.) to 2 cm (0.8 in.) oval patches appear in batches on the abdomen, chest, back, arms, and legs. Patches sometimes spread to the neck but rarely to the face.
  • Patches on the back are often vertical and angled to form a "Christmas tree" or "fir tree" appearance.
  • Mild itching is a problem for about half of the people who get the rash.
  • The rash usually lasts 6 to 8 weeks, but it can last up to several months.

In rare cases, the rash may take other forms. Rounded bumps (papular rash) may be seen in young children, pregnant women, and people who have dark skin. Blisters (vesicular rash) may be seen in infants and young children. In some people, the herald patch may not appear, or two herald patches may appear close together.

Before the herald patch appears, you may feel tired and as though you have a cold. You may have a headache, nausea, sore throat, and loss of appetite.

The pityriasis rosea rash is similar to the rash seen in other skin conditions, including ringworm of the skin, tinea versicolor, eczema, and psoriasis.

A rash similar to pityriasis rosea also can be caused by syphilis and by certain medicines such as antibiotics.

If you get a rash on the palms of your hands or the soles of your feet, see your doctor. This can be a sign of something more serious than pityriasis rosea.

Pagination