Pityriasis rosea
Pityriasis rosea is a relatively common skin condition that causes a temporary rash of raised, red scaly patches on the body.
It can affect anyone, but it's more common in older children and young adults (aged 10 to 35).
Symptoms of pityriasis rosea
Feeling unwell
Some people feel unwell for a few days before they get the rash, with symptoms such as a headache, fever and joint pain.
The herald patch
A single pink or red oval patch of scaly skin, known as the "herald patch", usually appears at least 2 days before a more widespread rash develops.
It ranges in size from 2cm to 10cm. It can appear on your tummy, chest, back or neck, and less commonly on the face or scalp, or near your genitals.
Widespread rash
A few days to 2 weeks later, a more widespread rash develops, which may continue to spread over the following 2 to 6 weeks.
It consists of smaller raised scaly patches that usually range in size from 0.5cm to 1.5cm. Most people get many patches across their chest, back, tummy, neck, upper arms and upper thighs. The face is usually unaffected.
In light-skinned people, the patches are usually a pinkish-reddish colour. In dark-skinned people, the patches can sometimes be grey, dark brown or black.
The rash isn't painful, but it can sometimes be itchy.
Both the herald patch and rash usually last for 2 to 12 weeks, although they can last for up to 5 months.
After the rash has gone, you may have some darker or lighter areas of skin. These should return to normal within a few months and won't leave permanent scarring.
When to see your GP
See your GP if you have an unexplained rash. They'll usually be able to confirm whether it's pityriasis rosea, or another skin condition such as eczema, psoriasis or ringworm.
If your GP is uncertain, they may refer you to a skin specialist (dermatologist).
Treating pityriasis rosea
Pityriasis rosea usually clears up without treatment within 12 weeks. Treatment isn't needed unless you experience discomfort and itching.
Possible treatments for pityriasis rosea include:
- emollients – creams that moisturise and soothe the skin; some emollients can be used as soap and are often recommended because normal soap can irritate the rash; you can buy these over the counter from most pharmacists
- steroid creams or ointments – such as hydrocortisone and betamethasone cream; they're prescribed by your GP and can reduce swelling and relieve itching
- antihistamines – if you're having trouble sleeping because of the itching, your GP may prescribe an antihistamine that will make you feel sleepy, such as hydroxyzine or chlorphenamine
- UVB light therapy – if other treatments don't work, you may be referred for UVB light therapy
What causes pityriasis rosea?
It's not known what causes pityriasis rosea. One theory is that the rash may be caused by a viral infection.
Pityriasis rosea isn’t contagious and can't be spread to other people through physical contact.
Pityriasis versicolor
Pityriasis versicolor is another common skin condition that can be confused with pityriasis rosea, as the rash may look similar.
But there are important differences between the two. Pityriasis versicolor is caused by a yeast infection and can be treated with antifungal medicines, including antifungal creams and antifungal shampoos.