Pityriasis rosea is a common skin rash. It usually begins as a large circular or oval spot on the abdomen, back or chest, though it can appear anywhere. This is then followed over the next week or two by new, round to oval lesions that appear over the trunk and arms. It can last anywhere from a few weeks to several months.
Though the rash is harmless, see a skincare provider for an accurate diagnosis and help with bothersome symptoms.
What Causes Pityriasis Rosea?
The cause of pityriasis rosea is unknown, but it’s likely a virus. Some evidence suggests it may be brought on by one of two common types of herpes virus (not the strains that cause cold sores). It’s not thought to be contagious.
Who Gets Pityriasis Rosea?
Anyone can develop pityriasis rosea, but most people who do are between the ages of 10 and 35 and healthy. The rash is uncommon in people over the age of 60.
Pityriasis rosea most often occurs in the spring and fall. It’s also common during pregnancy. If you’re pregnant and think you may have it, call your obstetrician.
Symptoms of Pityriasis Rosea
Pityriasis rosea typically begins with a slightly raised, circular or oval patch known as a herald patch. The patch can be as large as several inches across and may be scaly, especially at the center. Within a week or two, smaller patches or bumps appear and continue to spread over time.
In darker skin, the herald patch and bumps usually look brownish, grayish or purplish. People with lighter skin are more likely to develop smaller patches instead of bumps, and the patches typically look pinkish or salmon-colored.
The rash can cause itching, which in some cases can be severe. Some people get a sore throat, headache, fatigue, achiness or fever before the rash appears.
The rash resolves on its own, but it may take six to eight weeks or even several months. People with darker skin sometimes develop flat brown spots that remain after the rash disappears. The spots usually fade over the course of a year.
Diagnosing Pityriasis Rosea
A dermatologist can usually diagnose pityriasis rosea with a quick visual exam. An accurate diagnosis is important to rule out other conditions such as psoriasis, hives, ringworm, syphilis rash and an allergic reaction to medication. Skin changes on the breast that resemble pityriasis rosea may in fact be signs of breast cancer.
If necessary, the skincare provider may order blood tests to rule out syphilis or perform a small skin scraping and/or skin biopsy for further examination.
Pityriasis Rosea Treatment
The rash goes away on its own, so treatment isn’t usually necessary; however, if the rash is symptomatic (itching), a dermatologist might prescribe oral antihistamines, topical steroids or modest exposure to ultraviolet B (at an in-office visit) or sunlight.
There are steps you can take to make yourself more comfortable while you have the rash. An over-the counter antihistamine can ease the itching, as can cool compresses and lukewarm oatmeal baths. (Avoid hot baths and hot tubs as heat can aggravate the rash.) An over-the-counter hydrocortisone cream can be used on small areas of the skin in people age 12 and over. Follow the directions on the package. Use only gentle soaps — no deodorant soap.
Medical Review By: Ted Schiff, MD