The rash can affect adults and children alike but is most common in those aged from 10 to 35 years.
The rash is also likely to occur during pregnancies. While pityriasis rosea is a benign skin condition, there is a chance that it may have adverse effects on the newborn.
Pityriasis rosea commonly affects people aged 10 to 35 years old and a first symptom may be a fever or a headache.
A general feeling of being unwell may last for a few days before the first sign of the rash appears.
Itching is one of the prominent symptoms of the rash. Around 50 percent of people with pityriasis rosea may experience an itch.
The main rash itself is typically preceded by the appearance of a single oval patch known as the "herald" or "mother" patch.
This patch is usually pink with a darker border and often appears between 2 days and 2 weeks before the main rash develops over a much wider area.
The herald patch can measure from 2 to 10 centimeters (cm). It most often appears on the stomach, chest, back, or neck. Less frequently, it can develop on the scalp, face, or even near the genitals.
While it may take anything from a couple of days to 2 weeks for a wider rash to develop, it can carry on spreading for up to 12 weeks.
This widespread rash is made up of a mass of smaller patches, or plaques, that cover more parts of the body. The affected areas may include the upper arms and upper thighs.
These areas tend to be areas where the skin is more relaxed, such as along cleavage lines and on both sides of the upper trunk. The wider rash does not usually affect the face.
People with light-colored skins tend to develop a pinkish-red rash, while those with darker skins can expect to see gray, dark brown, or even black patches.
Research into pityriasis rosea during early pregnancy suggests that it could cause miscarriage, with researchers finding it in 8 of 61 women studied. Some women experienced premature delivery and other problems either before or after the birth itself.
Pityriasis rosea may be said to be atypical when the diagnosis has been difficult. An atypical pityriasis rosea rash is often marked by:
- an unusual appearance, including small bumps, blisters, weal-like patches, and bruising
- large patches that may merge or run into others
- unusual distribution of skin lesions, often affecting folds of relaxed skin, such as around the armpits, groin, and breasts
- inclusion of mucosal sites, for example, mouth ulcers
- a single herald patch that is not followed by a widespread rash
- several or no herald patches
- larger than usual number of plaques
- severe itch
- a longer course of disease than usual
- disease recurring a number of times
What causes pityriasis rosea?
No one knows what causes pityriasis rosea. According to the American Academy of Dermatology (AAD), it is not an allergy, and fungi and bacteria do not cause it.
One theory suggests that a viral infection, such as herpes viruses 6 and 7 causes the rash. However, unlike other illnesses caused by viruses, pityriasis rosea cannot transfer to other people through physical contact. In rare cases, the rash develops as a side effect of some drugs.
Symptoms of pityriasis rosea may be relieved by over-the-counter treatments such as moisturizing creams.
Anyone who develops an unexplained rash should see a doctor. If the person has pityriasis rosea, the doctor will be able to recommend the best medication to treat any itching the person may have.
While the symptoms mentioned above may be caused by pityriasis rosea, they could also be caused by a different skin condition. Other conditions that a doctor will consider, include:
If a doctor is in doubt over the diagnosis, they may refer the individual to a skin specialist (dermatologist).
Pityriasis rosea usually clears up within 12 weeks, without the need for any medical treatment.
The rash is not painful but, like many other rashes, it can be both irritating and itchy. Fortunately, these symptoms can be relieved quickly and easily.
Possible treatments include:
- Skin-soothing and moisturizing creams: Use creams in place of soap to avoid the irritation that soaps can cause. These are available over the counter from most pharmacists.
- Steroid creams or ointments: Hydrocortisone reduces redness, itching, and swelling. Betamethasone treats the itching and redness along with any discomfort caused by various skin conditions.
- Antihistamines: Commonly used to combat allergic reactions, doctors may prescribe them to anyone who has difficulty sleeping because of the itching.
Home remedies for the rash include the use of neem, coconut oil, oatmeal, catechu paste, or aloe vera.
People are also advised to use lukewarm water when taking a shower or bath. If skin becomes overheated, the rash can worsen and become more visible for a while.