Images of Pityriasis Rosea (9)
Pityriasis rosea (PR) is a common rash that usually occurs on the back, chest, and abdomen. It starts fairly quickly, lasts about 6-8 weeks, and is usually not itchy.
The cause of pityriasis rosea is not known, but it may be caused by infection with a virus.
Who's At Risk?
Pityriasis rosea can occur in people of any age, race / ethnicity, or sex, but it is most common in older children and young adults (those aged 10-40 years).
Signs & Symptoms
The most common locations for pityriasis rosea include the:
- Upper back.
- Upper arms.
Pityriasis rosea usually begins with a single scaly plaque (a raised area on the skin) ranging from 2-5 cm in size. This first patch is called a “herald patch,” and it is usually located on the trunk, neck, or upper arms. The herald patch is followed 1-3 weeks later by the development of a widespread rash with smaller (0.5-2 cm) oval, scaly papules and plaques on the trunk and upper arms. These papules and plaques form a “Christmas tree” pattern on the back. In an uncommon type of pityriasis rosea, the rash may be concentrated in the armpits and groin or on the face, forearms, and shins. In lighter skin colors, the rash can be any shade of pink or red. In darker skin colors, the rash may appear dark red, purple, or darker brown than the normal surrounding skin.
Some people report feeling mildly ill (headache, stuffy nose, muscle aches) for 1-2 weeks before the herald patch forms. Additionally, some people experience itching with pityriasis rosea. Becoming overheated by exercising or taking a hot shower may increase itching or make the rash more apparent.
Pityriasis rosea goes away on its own (is self-limited), typically within 6-8 weeks, without treatment. However, the rash often leaves behind patches of lighter (hypopigmented) or darker (hyperpigmented) skin; these patches are more obvious in darker skin colors and may take months to return to their normal color.
The herald patch of pityriasis rosea may be mistaken for ringworm (tinea corporis), but over-the-counter antifungal creams do not improve it. Similarly, the herald patch may look like eczema, but over-the-counter hydrocortisone creams also do not improve it.
Itching with pityriasis rosea can sometimes be reduced with:
- Oatmeal baths.
- Lukewarm (rather than hot) baths and showers.
- Antihistamine pills such as fexofenadine (Allegra), cetirizine (Zyrtec), or loratadine (Claritin) in the daytime and diphenhydramine (Benadryl) at bedtime.
Other than relieving the itch, there are no self-care measures for pityriasis rosea. Although the rash should go away on its own within 6-8 weeks, see a medical professional for evaluation of any widespread rash.
In most cases the medical professional will be able to diagnose the rash by examining your skin. If the rash is atypical, a skin biopsy may be required. These are usually performed by a dermatologist.
In addition, the medical professional may want to do blood tests for other medical conditions.
Because pityriasis rosea is benign and self-limited, no treatment is required. However, some people with pityriasis rosea have mild-to-severe itching, in which case your clinician may suggest:
- Moisturizing creams or lotions.
- Topical menthol-phenol lotions.
- Prescription topical corticosteroid (cortisone) creams or lotions.
- Oral antihistamine pills.
- Oral corticosteroid pills or an oral antibiotic or antiviral (if the pityriasis rosea is very severe).
If you develop a patch of pink, purple, or brown scaly skin that does not respond to over-the-counter antifungal creams or hydrocortisone cream, or if you develop a widespread rash, see a dermatologist or another medical professional for evaluation.
Be prepared to discuss the following with the medical professional:
- The course of the rash (when it started, whether or not there was a herald patch, etc)
- What treatments, if any, you have tried
- Whether or not any friends or relatives have a similar rash
- Your recent sexual history
- Your medication history (including the names of any medications or supplements you have taken within the last month)
Bolognia J, Schaffer JV, Cerroni L. Dermatology. 4th ed. Philadelphia, PA: Elsevier; 2018.
James WD, Elston D, Treat JR, Rosenbach MA. Andrew’s Diseases of the Skin. 13th ed. Philadelphia, PA: Elsevier; 2019.
Kang S, Amagai M, Bruckner AL, et al. Fitzpatrick’s Dermatology. 9th ed. New York, NY: McGraw-Hill Education; 2019.
Last modified on February 27th, 2023 at 8:37 pm