Pityriasis Rosea – A Common and Troubled Rash

Pityriasis rosea is a fairly common skin condition that causes a rash. It can occur at any age, but is most common between the ages of 10 and 35. It is a benign condition, but for some it can be bothersome, cause itching and last for weeks to months.

What Causes Pityriasis Rosea?

The exact cause of pityriasis rosea is unknown. There is some evidence that it may be due to a viral infection.

What Are the Signs and Symptoms of Pityriasis Rosea?

• Cold or flu symptoms may precede about two-thirds of cases.

• A larger 2 to 10 cm oval reddish patch may “herald” the onset of the generalized pityriasis rosea rash, hence the name “messenger patch”. It is usually found in the abdomen, but can also be found elsewhere.

• 1 to 2 weeks after the herald patch, a pink, oval-shaped, scaly rash appears on the trunk and may extend to the proximal limbs in a characteristic “Christmas tree” distribution. The face is usually spared.

• In approximately 25% of cases, the rash is not itchy. The other 25% have severe itching and the remaining 50% have a mild to moderately itchy rash.

• The rash usually lasts 6 to 8 weeks, but can sometimes last several months.

How Is Pityriasis Rosea Diagnosed?

The diagnosis of pityriasis rosea is made by careful examination of the rash and its distribution. If you are in doubt about the diagnosis, you may need to see a dermatologist to rule out other conditions such as ringworm (tinea), psoriasis, eczema, drug rashes, or other viral rashes. Sometimes a skin biopsy may be required.

How to Treat Pityrisis Rosea?

Usually no treatment is required as it usually resolves spontaneously within 6 to 8 weeks.

Antihistamines or topical steroids are sometimes prescribed when itching is bothersome. It has been found that exposing the rash to sunlight makes it go away more quickly. Therefore, treatment with ultraviolet light (most useful only in the first week of the eruption) has been used to accelerate resolution.

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