Pityriasis rosea is a common skin rash that does not cause any significant or long-term health effects. It most often afflicts people between the ages of 10 and 35, and usually occurs once in a lifetime. Initially, pityriasis rosea presents itself as a single, large, pink patch that has a well-defined scaly border. In subsequent weeks, oval patches will appear and often form a symmetrical pattern resembling a Christmas tree, which is why it is often referred to as “Christmas tree rash.” In some cases this rash may be accompanied by itching. Pityriasis rosea typically lasts for six to eight weeks and will usually resolve itself without any medical intervention.
The hallmark symptom of pityriasis rosea is the appearance of a rash. The rash often begins with a herald patch, which is a large, slightly raised, round patch that has a scaly border. The size of the herald patch can range from 2 to 10 centimeters. You may experience some of the following symptoms before a herald patch appears:
- Stuffy nose
- Sore throat
- Low grade fever
- Loss of appetite
A few days to weeks after the herald rash appears, you may experience:
- The appearance of small oval patches. These patches are small (1 to 2 centimeters) and typically appear on the abdomen, chest, back, arms and legs. These patches often form a vertical and angled pattern that resembles a Christmas tree.
- Itching. 50 to 75 percent of the people who have pityriasis rosea will experience mild to severe itching. A quarter of those with pityriasis rosea will not experience any itching.
The color of the rash may vary with the pigment of your skin. For those with lighter skin, pityriasis rosea will appear scaly and pink. However, for those with darker skin, the rash may be gray, dark brown or black. Furthermore, the rash’s shape and texture may also vary between individuals. Young children and pregnant women may experience a papular rash, which consists of small round bumps. Pityriasis rosea may also present itself as blisters (vesicular rash) in infants and young children.
The cause of pityriasis rosea is unknown. However, some experts believe that pityriasis rosea may be caused by a virus specifically certain strains of the human herpes virus (HHV6 or HHV7). Pityriasis rosea isn't believed to be contagious and should only occur at one time in a person’s life. However, there have been instances where certain individuals suffer from the recurrence of Christmas tree rash.
In order to diagnose pityriasis rosea, a doctor will initially perform a comprehensive physical exam and take a medical history. Specifically, your doctor will closely examine the rash. A diagnosis can be difficult when only the herald patch is visible because this stage of pityriasis rosea mimics the rash often associated with ringworm, eczema, or secondary syphilis. In order to rule out other causes for the rash, a doctor may order:
- A blood test
- A skin biopsy
A diagnosis of pityriasis rosea is easier to make once the second stage of pityriasis rosea appears.
Pityriasis rosea does not require any medical treatment and will usually go away in six to eight weeks. However, a doctor may prescribe or recommend a treatment to ameliorate the itchiness associated with pityriasis rosea.
The following treatments may be recommended to help relieve itching:
- Keep the itchy area cool and moist. Apply washcloths soaked in ice water. Avoid taking hot showers or baths.
- Take an oatmeal bath. You may use over the counter products such as Aveeno Colloidal Oatmeal bath or you may use oatmeal that you have at home. Additionally, you can take an oatmeal sponge bath. In order to do this, wrap one cup of oatmeal in a cotton cloth and boil as you would to cook oatmeal. Use this as a sponge and bathe in cool water without soap.
- Apply 1 percent hydrocortisone (found over the counter) to the itchy areas. Use the cream very sparingly on the face or genitals.
- Take an over-the-counter antihistamine. Don't give antihistamines to your child unless you've checked with the doctor first.
- Apply a moisturizer lotion to the skin while it is damp.
- Wear cotton or silk clothing. Avoid wearing wool and acrylic fabrics next to your skin.
- Use as little soap as possible. When bathing utilize a small amount of a mild soap.
Since the cause of pityriasis rosea is unknown, there are currently no suggested preventative therapies. Contact your physician regarding any complications with skin and itching. You may want to seek medical attention for recurring pityriasis rosea. Recurrence of Christmas tree rash is rare, although it does happen for certain individuals.