Pityriasis rosea

What is pityriasis rosea?

Pityriasis rosea (PR) is a common, benign skin rash that mostly affects the back, chest and abdomen.

The rash is painless most of the time and is not a sign of any disease, but it can sometimes cause itchiness or discomfort.

The rash is most common in teenagers and young adults, but it can affect patients of any age. It affects males and females equally.

How does pityriasis rosea affect the body?

Pityriasis rosea typically starts with a single, large, red, scaly oval rash called a herald patch on the trunk (back, chest or abdomen), neck or upper arms. One to three weeks later, it develops into widespread smaller patches of pink to red, scaly skin on the trunk and upper arms. This second rash may form a Christmas tree pattern on the back.

PR mainly affects the trunk, but children can sometimes have unusual forms of it and develop rashes on the face, wrists and legs.

PR can cause some discomfort, but it is not a serious condition. Some children report feeling mildly ill (headache, stuffy nose, muscle aches) for a week or two before the herald patch forms. The rash may also cause some itchiness.

What causes pityriasis rosea?

The cause of pityriasis rosea is not known, but it is thought to result from a virus, in particular herpes viruses 6 and 7. This would explain the mild symptoms of illness before the herald patch appears.

How is pityriasis rosea diagnosed?

Your child’s doctor can usually diagnose PR simply by examining your child and asking about their symptoms and medical history. If the diagnosis is not clear, the doctor may order a skin biopsy or use other tests, such as scraping (rubbing the skin to obtain a small sample), to rule out a fungal infection.

How is pityriasis rosea treated?

Pityriasis rosea does not pose any danger and is not contagious. It generally disappears within six to eight weeks without any treatment.

There are a number of things you can do to help your child while their rash heals.

• Expose the affected skin to five to 10 minutes of direct sunlight for several days. The ultra-violet radiation may help reduce itching and help the rash disappear more quickly.
• Keep your child’s skin moisturized and consider giving over-the-counter antihistamines to control itchiness.
• For severe itchiness, ask your child’s doctor about prescribed steroid creams or lotions.
• Avoid situations that could cause your child to become overheated, as this can increase itchiness and make the rash more obvious. For instance, have your child bathe or shower in lukewarm instead of hot water and encourage them to avoid strenuous physical activity.

Once the rash heals, it often leaves patches of lighter or darker skin. These patches are called post-inflammatory hyper/hypopigmentation and may take months to return to their normal colour.

When to see a doctor for pityriasis rosea

See your child’s doctor if your child:

• has severe itching
  
• is in pain
• develops symptoms of infection such as fever, discomfort or fatigue.