Pityriasis Rosea

Pityriasis rosea is a rash that usually appears on the chest, abdomen, and back. It may also appear on the upper arms and upper legs. It usually begins as a single patch, and then more patches start to develop. The rash may cause mild itching, but it normally does not cause other problems. It usually goes away without treatment. However, it may take weeks or months for the rash to go away completely.

What are the causes?

The cause of this condition is not known. The condition does not spread from person to person (is not contagious).

What increases the risk?

This condition is more likely to develop in:

• Persons aged 10–35 years.
• Pregnant women.

It is more common in the spring and fall seasons.

What are the signs or symptoms?

The main symptom of this condition is a rash.

• The rash usually begins with a single oval patch that is larger than the ones that follow. This is called a herald patch. It generally appears a week or more before the rest of the rash appears.
• When more patches start to develop, they spread quickly on the chest, abdomen, back, arms, and legs. These patches are smaller than the first one.
• The patches that make up the rash are usually oval-shaped and pink or red in color. They are usually flat but may sometimes be raised so that they can be felt with a finger. They may also be finely crinkled and have a scaly ring around the edge.

Some people may have mild itching and nonspecific symptoms, such as:

• Nausea.
• Loss of appetite.
• Difficulty concentrating.
• Headache.
• Irritability.
• Sore throat.
• Mild fever.

How is this diagnosed?

This condition may be diagnosed based on:

• Your medical history and a physical exam.
• Tests to rule out other causes. This may include blood tests or a test in which a small sample of skin is removed from the rash (biopsy) and checked in a lab.

How is this treated?

Treatment is not usually needed for this condition. The rash will often go away on its own in 4–8 weeks. In some cases, a health care provider may recommend or prescribe medicine to reduce itching.

Follow these instructions at home:

• Take or apply over-the-counter and prescription medicines only as told by your health care provider.
• Avoid scratching the affected areas of skin.
• Do not take hot baths or use a sauna. Use only warm water when bathing or showering. Heat can increase itching. Adding cornstarch to your bath may help to relieve the itching.
• Avoid exposure to the sun and other sources of UV light, such as tanning beds, as told by your health care provider. UV light may help the rash go away but may cause unwanted changes in skin color.
• Keep all follow-up visits as told by your health care provider. This is important.

Contact a health care provider if:

• Your rash does not go away in 8 weeks.
• Your rash gets much worse.
• You have a fever.
• You have swelling or pain in the rash area.
• You have fluid, blood, or pus coming from the rash area.

Summary

• Pityriasis rosea is a rash that usually appears on the trunk of the body. It can also appear on the upper arms and upper legs.
• The rash usually begins with a single oval patch (herald patch) that appears a week or more before the rest of the rash appears. The herald patch is larger than the ones that follow.
• The rash may cause mild itching, but it usually does not cause other problems. It usually goes away without treatment in 4–8 weeks.
• In some cases, a health care provider may recommend or prescribe medicine to reduce itching.