Pityriasis rosea is a mild skin rash with a pink, scaly and inflamed appearance. The condition is quite common, and it is not serious. It is most common in children and young adults but can occur at any age.

The rash usually lasts between 1 to 3 months and leaves no permanent marks. People with dark skin may notice lasting brown spots after the rash has healed.

Once it is gone, pityriasis rosea usually does not come back.

The first sign of pityriasis rosea is usually a round or oval patch on the chest, belly or back. The patch is usually pink or tan and is referred to as a “herald patch” as it comes first, before the other skin lesions.

Over the next couple of weeks, smaller pink or tan patches appear on areas such as the back, neck, arms or legs. The pattern of these patches can look like drooping pine-tree branches and is sometimes called a “Christmas tree pattern”.

If you have pityriasis rosea, you may also notice that you:

• feel tired
• have aches and pains
• are itchy, sometimes severely
• have a cold, sore throat or fever before the rash develops

When should I see my doctor?

Contact your doctor if your rash gets worse, it gets swollen or infected, or it does not go away in 8 weeks.

If you develop pityriasis rosea when you are pregnant, see your doctor, as in rare cases it can lead to complications.

Pityriasis rosea is caused by a viral infection. The virus has recently been identified as one of the herpes viruses.

Children and young adults are more susceptible, for reasons unknown. Recurrences are rare - a person who develops the skin rash has only a two per cent chance of experiencing it again.

Pityriasis rosea doesn’t seem to be highly contagious, but other members of the household may prefer to practise more stringent personal hygiene just for peace of mind.

Doctors can usually diagnose the rash of pityriasis rosea just by looking at it. Your doctor may take a scraping for testing or do a blood test to rule out other conditions.

Most treatments for pityriasis rosea aim to soothe the skin and relieve itching. They include:

• corticosteroid cream or ointment, which may also decrease redness
• using a gentle soap-free wash
• using moisturiser

If you have pityriasis rosea, avoid having a hot bath or sauna, as heat can make the itching worse.

Natural or artificial sunlight can help fade the rash, but in some people, this can cause lasting dark patches.

Pityriasis rosea is usually harmless and has no complications. Occasionally, it can cause pregnancy complications, including miscarriage and premature birth. If you have pityriasis rosea and are pregnant, you should see your doctor.

Another complication of pityriasis rosea is prolonged skin discolouration.