Pityriasis rosea: symptoms, treatment and how long it lasts

Most people do not need any treatment. The NHS says it usually gets better on its own within a few months, and that it might get worse before it goes away completely. The British Association of Dermatologists (BAD) says there is no need to treat the rash or change your usual activities if it is not causing symptoms.

If the rash is itchy or uncomfortable, the NHS says a pharmacist might advise using an emollient on the rash, taking antihistamine tablets to help with itching and avoiding soaps and body washes. BAD suggests a fragrance-free moisturiser and a soap substitute, and says a mild steroid cream such as hydrocortisone ointment can be applied twice a day if the rash is still uncomfortable.

NICE Clinical Knowledge Summaries (CKS) says for people with itch an emollient or a mild or moderately potent topical corticosteroid may give symptomatic relief, and that a sedating oral antihistamine at night may be considered if itching affects sleep.

If these do not work or the rash is severe, the NHS says your GP may recommend steroid cream or refer you to a skin specialist (dermatologist). BAD says a stronger steroid or ultraviolet light treatment in a dermatology unit may be considered for severe itch, and mentions limited evidence that early antivirals or antibiotics may speed clearance, which is rarely required.

The NHS says the exact cause is not known and it may be caused by a virus. BAD says it has been associated with some viruses in the herpes family, the same family as the cold sore virus, but that the cause is still not known. It says it can occur in clusters, such as in schools or families, and is more frequent in winter.

BAD says it is not hereditary and that the risk of passing it on to anyone else is very low, while the NHS says pityriasis rosea cannot spread from person to person. NICE CKS says it mainly affects people aged 10 to 35 years and is slightly more common in females.

The main symptom is a rash. The NHS says some people get flu-like symptoms a few days before it appears, such as tiredness, a sore throat, a high temperature or a headache. BAD says most people feel fine apart from mild itch or discomfort.

The NHS describes two stages. The first is a single scaly herald patch, usually oval or round, slightly raised and about 2cm to 5cm across, which usually appears on the chest, thigh, upper arm or neck. About 5 to 15 days later a widespread rash of small scaly spots appears, usually on the chest and back, though it can appear on the arms or legs, and in children on the face or scalp. It usually appears in the same place on both sides and may be itchy.

NICE CKS says the multiple lesions are circular or oval, typically 0.5 to 1 cm in diameter, slightly scaly at the edge, and form a Christmas tree pattern on the upper back and chest. BAD compares the pattern to the branches of a fir tree and says it is unusual for the rash to affect the hands, feet or face.

The sources give slightly different ranges, which fits a condition that varies between people. BAD says it lasts about 6 to 8 weeks. NICE CKS says new crops of lesions can continue to appear for up to 6 weeks, and that the rash will usually settle without treatment within 2 to 3 months but may take up to 5 months to disappear. The NHS says within a few months.

After the rash has gone, the NHS says you may have some darker or lighter areas of skin, which may be more obvious on brown or black skin, and which should go back to normal within a few months without permanent scarring. BAD says these changes may last for several months or longer before fading.

See a GP if the rash has not gone away after 3 months, as the NHS advises. BAD says that if the rash lasts longer than two months or there is doubt, a doctor may recommend a small skin biopsy or blood tests to rule out other rashes.

The NHS says other conditions can have similar symptoms, and that you should not try to diagnose the problem yourself. Scaly spots could be psoriasis or eczema, and a single round patch could be ringworm. BAD says the herald patch can be confused with ringworm, which can be ruled out by a skin scraping if needed. There is no diagnostic test, and the typical story of a herald patch followed by a widespread scaly rash is usually enough for diagnosis.

The NHS gives urgent advice here: call your midwife, maternity unit, GP or NHS 111 immediately if you have a new rash and you are pregnant. It says getting pityriasis rosea in the first 15 weeks of pregnancy has been linked with miscarriage and premature birth.

NICE CKS takes a measured line for clinicians. If pityriasis rosea develops in the first trimester, women should be reassured that it is likely to be self-limiting and in most cases there is no harm to the pregnancy, and the case should be discussed with secondary care if the diagnosis is uncertain or there are obstetric concerns. A new rash in pregnancy still needs assessment, as other rashes can look similar.

The NHS says that in children the rash may appear on the face or scalp. BAD says there is no reason to keep children with pityriasis rosea away from school. The rash is most common between the ages of 10 and 35.

The NHS says to see a GP if you have a rash that is still itchy after trying pharmacy treatments such as emollients or antihistamines, or a rash that has not gone away after 3 months. Call your midwife, maternity unit, GP or NHS 111 immediately if you have a new rash and you are pregnant.

A rash that is blistering, painful, very widespread with fever or feeling very unwell is not the typical picture of pityriasis rosea and should be assessed promptly by a doctor.

Most people are diagnosed by a GP or pharmacist from the appearance and story, without tests. If the rash is severe, atypical or does not clear, the NHS says a GP may refer you to a dermatologist.

Some people choose to see a private dermatologist for reassurance or when the diagnosis is uncertain. In general terms the same approach applies: a clinical diagnosis, ruling out look-alikes with a skin scraping or blood test if there is doubt, and symptom relief. In pregnancy, ask your midwife or GP rather than waiting for a private appointment.