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. But it can cause serious problems in pregnant women.
See a picture of pityriasis rosea.
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. And there aren't signs that it is caused by a virus. But something irritates the skin and causes the rash.
What are the symptoms?
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.
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.
How is pityriasis rosea diagnosed?
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.
How is it treated?
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.
If the rash lasts more than 3 months, contact your doctor.
To relieve itching at home:
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