What is Pityriasis Rosea?

Mary McMahon
Mary McMahon

Pityriasis rosea is a skin condition where a distinctive spotty rash appears, sweeping out over the torso. It is not harmful or contagious, but can cause irritation and discomfort. Usually, it resolves without treatment, although some measures can be taken to make people feel more comfortable during the healing process. The rash may last anywhere from four weeks to two months, and may grow worse if people scratch or pick at it.

Pityriasis rosea rashes may appear around the feet and ankles.
Pityriasis rosea rashes may appear around the feet and ankles.

The cause of this medical issue is believed to be a viral infection. Many patients experience a respiratory infection before developing a single red spot known as the herald or mother rash, the first sign of pityriasis rosea. Over the next few days, other spots appear on the torso. They typically are wrinkled and scaly, with very crisp edges, and may be reddish in appearance. As they spread, they can trail all the way down the legs, appearing around the feet and ankles.

Patients with pityriasis rosea sometimes find it helpful to apply moisturizing creams to the skin or to soak in soothing baths. This can help with itching and will also gently lift away flakes of dead skin, keeping the rash looking neater. It is important to refrain from picking or scratching. This can open up the skin, creating lesions where bacteria may enter, and it can also contribute to the development of scarring. People who have trouble remembering to leave the rash alone can wear gloves or fitted clothes to make it harder to access the spots.

Exposure to low levels of ultraviolet light has been shown to be helpful for pityriasis rosea. Some patients may be advised to consider phototherapy under a lamp, or simply to spend some time outdoors. It is important to avoid too much exposure, as patients can develop sunburns and these may make the rash worse. People already using therapy lamps for conditions like seasonal affective disorder may find that their pityriasis rosea rashes resolve more quickly.

Fall and spring are common times for this skin rash to appear. It is usually easy to diagnose on the basis of clinical signs, but if there are any doubts, a doctor can take a scraping and send it to a pathologist. Patients should be aware that some people develop bubbles and blisters in addition to the classic flat, scaly rash; pregnant women and children in particular tend to experience this variant. Signs like fluid-filled blisters, in other words, do not rule out pityriasis rosea.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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