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Pityriasis rosea

What is pityriasis rosea and what causes it?

  • Pityriasis rosea is a common skin disorder of unknown cause and is usually mild.
  • Pityriasis rosea most often affects teenagers or young adults.
  • It may be caused by a viral infection but does not appear to be contagious.
  • It is not related to foods, medicines, or stress.

What are the symptoms of pityriasis rosea and what does the rash look like?

  • In at least one half of patients, the first symptoms of pityriasis rosea are nonspecific and consistent with a viral upper respiratory infection (the common cold)
  • A large single scaling pink patch, called the Herald Patch (see photo called Pityriasis Rosea), often appears first on the chest or back.
  • Within a week or two, smaller scaly patches appear every few days, mainly on the trunk but may spread to the thighs, upper arms and neck (see photo called Pityriasis Rosea 2).
  • The oval patches follow the line of the ribs like a fir tree (sometimes called a “Christmas tree pattern”).
  • Pityriasis rosea usually avoids the face, although sometimes a few spots spread to the cheeks.
  • Fungus infections, like ringworm, may resemble this rash.
  • Itching (pruritus) occasionally occurs.
  • Physical activity-like jogging and running, or bathing in hot water may cause the rash to temporarily worsen or reappear.

How long does ptyriasis rosea last and does it cause any long-term health problems?

  • Pityriasis rosea usually clears up by itself in about six to twelve weeks.
  • When clear, the skin returns to its normal appearance.
  • It leaves no scars, although pale marks or brown discoloration may persist for a few months in dark skinned people.

How can pityriasis rosea be treated?

Most cases usually do not need treatment but the following tips may help:

  1. Bathe or shower with plain water and bath oil, aqueous cream, or another soap substitute. Soap irritates the rash.
  2. Apply moisturizing creams to dry skin.
  3. For patients with severe itching, treatment with zinc oxide, calamine lotion, topical steroids, oral antihistamines, and even oral steroids may be recommended.
  4. Extensive or persistent cases can be treated by phototherapy (ultraviolet light) under the supervision of a dermatologist.