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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. But it can cause serious problems in pregnant women.
See a picture of 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. And there aren't signs that it is caused by a virus. But something irritates the skin and causes the rash.
Pityriasis rosea causes a rash.
The rash may take other forms. Rounded bumps (papular rash) may be seen in young children, pregnant women, and people with 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.
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.
Your doctor will diagnose pityriasis rosea by looking at the rash. Diagnosis can be hard when only the herald patch is visible, because the condition is often mistaken for ringworm or eczema at this time. After the rash appears, diagnosis is generally clear.
If the diagnosis is unclear, your doctor may do a potassium hydroxide (KOH) test to make sure the rash is not caused by a fungal infection. A skin sample may be taken from the infected area and examined under the microscope (biopsy). If the diagnosis is unclear in a sexually active person, a test for syphilis is often done.
Pityriasis rosea goes away without treatment. It usually lasts about 6 to 8 weeks. If the rash itches, you may wish to use skin lotions and lubricants to soothe itching. If symptoms are severe, your doctor may prescribe anti-inflammatory medicines such as corticosteroids to relieve itching and reduce the rash.
Although treatment isn't needed, antiviral medicines like acyclovir may shorten the time you have the rash, especially if you take them when the rash first starts.
Exposing the rash to sunlight may make it go away more quickly. But exposing your skin to the sun too long can result in sunburn and increase your risk of skin cancer.
If the rash lasts more than 3 months, contact your doctor.
To relieve itching at home:
- Blauvelt A (2008). Pityriasis rosea. In K Wolff et al., eds., Fitzpatrick's Dermatology in General Medicine, 7th ed., vol. 1, pp. 362–366. New York: McGraw-Hill.
Other Works Consulted
- Hall JC (2010). Other papulosquamous dermatoses. In JC Hall, ed., Sauer’s Manual of Skin Diseases, 10th ed., pp. 164–173. Philadelphia: Lippincott Williams and Wilkins.
- Muncaster A (2010). Pityriasis rosea. In MG Lebwohl et al., eds., Treatment of Skin Disease: Comprehensive Therapeutic Strategies, 3rd ed., pp. 571–572. Edinburgh: Saunders Elsevier.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Specialist Medical Reviewer||Amy McMichael, MD - Dermatology|
|Last Revised||November 3, 2011|
Last Revised: November 3, 2011
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