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Pityriasis Rosea

A rash of oval, pink, flat spots, most commonly affecting the trunk and limbs

  • Mainly affects young adults
  • Gender, genetics, and lifestyle are not significant factors

Pityriasis rosea produces a mild, pink rash. The condition most commonly occurs in young adults. It usually affects the trunk, arms, and upper thighs; more rarely, it affects the feet, hands, and scalp. The condition is thought to be caused by a viral infection.

What are the symptoms?

The symptoms change over time as the condition progresses. They usually develop in the following order:

  • An oval patch, 2–6 cm ( 3 / 4 –2 1 / 2 in) in diameter, known as a herald patch, appears. This patch resembles those that occur in ringworm.

  • About 3–10 days later, a number of smaller oval, pink, flat spots, 1–2 cm ( 3 / 8 3 / 4 in) in diameter, appears. The rash begins on the trunk, spreading across the abdomen, along the thighs and upper arms, and up towards the neck. The spots on the back usually occur in sweeping lines, resembling the shape of a Christmas tree.

  • A scaly margin may appear around the edges of the patches after a week.

Itching may occur and is occasionally troublesome. Although pityriasis rosea is not serious, it is important to consult your doctor to rule out conditions such as psoriasis and eczema.

Pityriasis rosea

Oval, pink, flat spots, shown here on the abdomen, are typical of pityriasis rosea, which may affect several parts of the body.

What might be done?

The distinctive rash makes the condition easy to diagnose. It usually clears up after about 6–8 weeks without treatment and is unlikely to reappear. If itching is troublesome, your doctor may prescribe a topical corticosteroid to relieve it.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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