Pityriasis rosea is a common self-limited rash that tends to happen in healthy teenagers and youngadults.   Most patients with this condition are between 10 and 35 years of age.

What Does Pityriasis Rosea Look Like?

There are several different forms of pityriasis rosea.  The most common of these starts with a "herald patch" in which one large scaly red patch is evident somewhere on the skin, most commonly on the trunk.  Hours or days later, smaller similar patches start to form.  Over several days, lots of new spots form, leading to a fairly widespread rash and striking appearance.  Sometimes these spots form what is known as a "christmas tree" distribution, in which the spots fall along angles on the back.

How Long does Pityriasis Rosea Last?

The rash usually lasts for 6-8 weeks and then heals on its own, although occasionally people have it for several months.  People with dark skin can sometimes develop dark patches that can last for months (hyperpigmentation).

What Pityriasis Rosea?

The exact cause of pityriasis rosea is unknown.  Most scientists think that it is a "viral exanthem", in which the body's immune system is responding to a viral infection.

Are There Other Symptoms Associated with Pityriasis Rosea?

Usually not.  About 5% of patients may have mild fever, headache or feel generally unwell before the rash starts.    The rash itself is entirely benign and is not dangerous in any way.

How is Pityriasis Rosea Treated?

Most cases of pityriasis rosea do not require treatment.  The rash resolves on its own.  Patients who are itchy and uncomfortable can be treated with topical cortisone medications.  Severe cases are sometimes treated with phototherapy (medical use of ultraviolet light) or cortisones given by injection.