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:
A few days to weeks after the herald rash appears, you may experience:
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 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:
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.