What is pityriasis rosea?
Pityriasis rosea is a relatively common skin condition, causing a distinctive skin rash of raised, red scaly patches across the body.
The condition will usually resolve by itself within 2-12 weeks and it doesn't pose a serious threat to your health.
In many cases, a single red, oval patch of scaly skin called a “herald patch” appears before the rash. This typically appears a few days to two weeks before the wider rash.
The rash is sometimes itchy.
Read more about the
.When to see your doctor
If you think that you may have pityriasis rosea, see your doctor to help confirm the diagnosis and ensure that other possible causes of your rash are not overlooked. Pityriasis rosea is not associated with any serious complications, so there’s no need to be concerned.
If you develop blistering, soreness, or involvement of your eyes, genitals or mouth, you should seek medical advice immediately, as this may indicate another more serious condition.
Read more about
.Why it happens
It's not known what causes pityriasis rosea. One theory is that the rash may be the result of a viral infection, although there's currently no hard evidence to support this.
Pityriasis rosea is not 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 other people.
Treating pityriasis rosea
In most cases, pityriasis rosea will clear up without any treatment. The rash usually goes away within twelve weeks, although it can sometimes last for up to six months.
Emollients (moisturisers),
and a type of medication known as an can be used to help relieve the itchiness.Read more about
.Who is affected
Pityriasis rosea is a relatively common skin condition, although precise statistics for the UK are not known.
Most cases of pityriasis rosea occur in older children and younger adults between 10 and 35 years old. However, cases have been reported in babies as young as 10 months old and elderly people in their eighties.
For unknown reasons, the condition affects women more often than men.
Most people only experience one episode of pityriasis rosea in their lifetime. Around 1 in 50 people have repeated episodes.
Symptoms of pityriasis rosea
The symptoms of pityriasis rosea may progress in three distinct stages. However, not everyone who has the condition will experience the first or second stages described below.
Initial symptoms
Some people with pityriasis rosea have initial symptoms a few days to a week before the skin rash appears.
These can include:
- a high temperature (fever) of 38ºC (100.4ºF) or above
- and/or an upset stomach
- lack of appetite
- joint pain
- a general sense of feeling unwell
These symptoms will usually pass by the time you reach the secondary rash stage (see below).
The herald patch
The next stage is usually the appearance of a 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 2-10cm (0.8-4 inches).
The patch usually appears on the trunk (the upper section of your body that includes the abdomen and chest) or neck. Less commonly, the patch can appear on the face, scalp, or on or near the genitals.
Secondary rash
A secondary 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 0.5 - 1.5cm. Most people will develop multiple patches across their trunk, 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 symmetrical ‘Christmas tree pattern’ on the upper back and a v-shape across the chest. They come together to form multiple downward slanting triangular lines that look similar to the branches of a fir tree.
The secondary 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 the secondary rash will clear within twelve weeks, although some symptoms occasionally persist for up to six 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.
When to seek medical advice
If you think that you may have pityriasis rosea, see your doctor to help confirm the diagnosis and ensure that other possible causes of your rash are not overlooked. Pityriasis rosea is not associated with any serious complications, so there’s no need to be concerned.
If you develop blistering, soreness, or involvement of your eyes, genitals or mouth, you should seek medical advice immediately, as this may indicate another more serious condition.
Diagnosing pityriasis rosea
Your doctor 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
(a skin condition that is often triggered by allergies), or a type of fungal skin infection known as .Further testing will usually include
, scraping of a small area of skin to check for the presence of fungus and a (where a small sample of affected skin is removed so that it can be examined under a microscope).Treatment for pityriasis rosea
As pityriasis rosea usually resolves by itself within two to twelve weeks, treatment is not usually necessary unless you experience uncomfortable itching.
There are three main treatments:
- emollients – skin creams that are designed to moisturise and sooth the skin
- topical corticosteroids – creams or ointments that contain steroid medication
- antihistamines – a type of medication widely used to treat allergy-related symptoms, such as itchiness
If these don't work, you may be referred to a dermatologist (a specialist in treating skin conditions) who may recommend a treatment called UVB light therapy.
These treatments are described in more detail below.
Emollients
are creams, ointments and lotions designed to help the skin retain moisture to relieve itchiness.You can use the emollient as often as is required to relieve itching. Apply the emollient 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. These types of emollients are available over the counter from most pharmacists.
Topical corticosteroids
You should visit your doctor if emollients fail to control the symptoms of itchiness. You may need additional treatments with a
. Topical corticosteroids are applied directly to the skin and include hydrocortisone or betamethasone cream.The main aim of topical corticosteroids is to reduce inflammation (redness of the skin) and to help relieve the symptoms of itching. It's usually recommended that you apply topical corticosteroid cream or ointment lightly to affected areas of skin once or twice a day - depending on the advice of your doctor.
If you use topical steroids 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 side effect is usually temporary and should pass once your body gets used to the medication.
Antihistamines
If you're having trouble sleeping due to itching, your doctor may prescribe a sedating
, such as hydroxyzine or chlorphenamine.Sedating antihistamines are antihistamines originally designed to treat allergic conditions such as hay fever, but it was subsequently found that they caused drowsiness in many people. This is a useful side effect in some cases because the drowsiness will help you sleep better.
You usually need to take the medication just before you go to bed. Many people still feel quite drowsy when they wake up the following morning. If this is the case, avoid driving or using tools or machinery.
UVB light therapy
If your symptoms fail to respond to the above treatments, 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 is not the same as using a sunbed.
However, there are some uncertainties about how effective UVB light therapy is for pityriasis rosea. Although some medical trials suggest it can help relieve itchiness, others have found it only helps improve the appearance of the rash (without relieving itchiness) during the first few weeks of the condition.
Some people find exposure of their skin to natural sunlight for short periods can also be useful, although you should take care not to stay in the sun too long because prolonged exposure to the sun can damage your skin and increase your risk of developing skin cancer.
Other treatments
A number of other treatments have also been suggested for pityriasis rosea, but their use is controversial. They include:
- aciclovir – an antiviral medication that was originally designed to treat herpes infections
- erythromycin – an antibiotic that's designed to treat bacterial infections
- oral (tablet) corticosteroids
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.