Pityriasis rosea is a relatively common skin condition that causes a temporary skin rash of raised, red scaly patches on the body.
The rash can be very itchy and usually clears within 2-12 weeks, but on rare occasions can last up to 5 months. It doesn't usually leave scars, although some people have discolouration of their skin afterwards, which can last for a few months.
In many cases, a single pink or red oval patch of scaly skin called a "herald patch" appears on your chest, back or tummy about 5-15 days before the rash develops.
Read more about the symptoms of pityriasis rosea.
When to see your GP
If you have an unexplained rash, see your GP for a diagnosis. They will usually be able to confirm if it is pityriasis rosea, or something else such as eczema, psoriasis or a fungal skin infection.
If there is some uncertainty, you may be referred to a dermatologist.
If you develop blisters or soreness, or your eyes, genitals or mouth are affected, seek medical advice immediately as this may indicate another, more serious condition.
Why it happens
It's not known what causes pityriasis rosea. It's possible that the rash may be the result of a viral infection, although there's currently no evidence to support this.
Pityriasis rosea isn't contagious and can't be spread to other people by physical contact, so there's no need for someone with the condition to be kept away from others.
Treating pityriasis rosea
In most cases, pityriasis rosea will clear up without any treatment. The rash usually goes away within 12 weeks, although it can sometimes last for up to 5 months.
Read more about treating pityriasis rosea.
Who is affected
Pityriasis rosea can affect anyone, but older children and young adults (aged 10-35) are most commonly affected.
The condition affects women more often than men. It's also more common during spring and autumn.
Most people only experience one episode of pityriasis rosea in their lifetime. Around 1 in 50 people have repeated episodes.
Pityriasis versicolor is another common skin condition that can be confused with pityriasis rosea, as the rash may look similar.
However, there are important differences between the two. Pityriasis versicolor is caused by a yeast infection and can be treated with antifungal creams or anti-dandruff shampoos.
Read more about pityriasis versicolor.
Symptoms of pityriasis rosea
The symptoms of pityriasis rosea may progress in three stages. However, not everyone will experience the first or second stages described below.
A small number of people with pityriasis rosea may feel generally unwell a few days to two weeks before the skin rash appears. Symptoms can include:
These symptoms usually pass by the time the rash appears.
The herald patch
The next stage is usually the appearance of a pink or red oval patch of scaly skin that grows larger over the course of a few days. This is known as the "herald patch". It ranges in size from 2cm to 10cm (0.8-4 inches).
The patch usually appears on your tummy, chest, back or neck. Occasionally, the patch can appear on your face or scalp, or near your genitals.
A skin rash will usually develop within a few days to two weeks after the appearance of the herald patch, and it may continue to spread over the following two to six weeks.
The rash is made up of smaller raised scaly patches that usually range in size from 0.5cm to 1.5cm. Most people will develop 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 patches usually form a "Christmas tree pattern" on the upper back and a v-shape across the chest.
The rash isn't painful, but it can be itchy. The itchiness can range from mild to severe. It's often made worse by sweating and wearing tight-fitting clothing.
In most cases, both the herald patch and skin rash will clear within 12 weeks, although occasionally it persists for up to five months.
After the rash has disappeared, you may notice some darkened or lightened areas of skin. These should return to normal within a few months. Pityriasis rosea doesn't cause scarring.
Diagnosing pityriasis rosea
Your GP should be able to diagnose pityriasis rosea by asking you about your symptoms and visually examining the rash.
Further investigations are only required if there is uncertainty over the diagnosis.
If there is some uncertainty, you may be referred to a doctor who specialises in treating skin conditions (dermatologist).
The dermatologist will be able to check whether your symptoms are caused by a condition other than pityriasis rosea, such as eczema (a skin condition that is often triggered by allergies), psoriasis or a type of fungal skin infection known as ringworm.
Further testing will usually include blood tests, scraping of a small area of skin to check for the presence of fungus and a biopsy (where a small sample of affected skin is removed so that it can be examined under a microscope).
Treating pityriasis rosea
As pityriasis rosea usually clears up by itself within 2 to 12 weeks, treatment is not usually necessary, unless you experience uncomfortable itching.
There are three main treatments:
If these don't work, you may be referred to a dermatologist, who may recommend a treatment called UVB light therapy.
The treatments are described in more detail below.
You can use an emollient as often as you like. Apply it gently in the direction of the hair growth and avoid vigorously rubbing the skin.
Some emollients are designed to act as a soap substitute and are usually recommended because normal soap can irritate the rash. You can buy these over the counter from most pharmacists.
Steroid creams or ointments
Visit your GP if emollients fail to control the itchiness. You may need to try a steroid cream or ointment, such as hydrocortisone or betamethasone cream.
Steroid creams and ointments reduce inflammation of the skin and help to relieve the itching. You usually apply it lightly to affected areas of skin once or twice a day.
If you use the cream as directed by your doctor, side effects are rare. Some people may experience a slight burning or stinging sensation when first applying the cream. This is usually temporary and should pass once your body gets used to the medication.
If you're having trouble sleeping because of itching, your GP may prescribe a sedating antihistamine, such as hydroxyzine or chlorphenamine. This causes drowsiness, which can help you sleep better. You usually need to take the medication just before you go to bed.
Antihistamines can make you feel quite drowsy the following morning, so you should avoid driving or using tools or machinery if this is the case.
UVB light therapy
If your symptoms don't respond to the treatments above, you may be referred for UVB light therapy. This involves the controlled exposure of your skin to ultraviolet light for a few seconds to minutes at regular intervals under the guidance of a specialist. This isn't the same as using a sunbed.
Some medical trials suggest it can help to relieve itchiness, while others have found it only helps to improve the appearance of the rash (without relieving itchiness) during the first few weeks of the condition.
Natural sunlight has been helpful to some people, but care should be taken not to stay in the sun too long.
A number of other treatments have also been suggested for pityriasis rosea, but their use and effectiveness is debatable. They include:
If you're offered these treatments, you should be aware that evidence of their effectiveness and safety when used to treat pityriasis rosea is limited.