Rashes can be confusing. Even though they can occur with many different conditions — skin diseases, viral or bacterial illnesses, and even stress — they can still have similar characteristics. This can make it difficult to figure out what may be causing a new rash. For example, a psoriasis rash sometimes resembles symptoms of another condition, pityriasis rosea.

Though psoriasis and pityriasis rosea share certain symptoms, they have different causes, treatments, and long-term complications. Mistaking these two skin conditions for one another is easy. If you’re living with psoriasis and experience any skin changes, it’s important to get a diagnosis from a health care provider, rather than assuming the change is from your current condition.

While uncommon, some people may have both conditions. Some members of MyPsoriasisTeam have discussed dealing with the two disorders at once. One member with psoriasis commented, “In the last 12 weeks I’ve been suffering with pityriasis rosea, and my psoriasis has been attacking it. Now I feel like I’m constantly on fire, have pins and needles, and am so sore.”

Read on to learn more about the differences between these conditions.

Pityriasis Rosea and Psoriasis: What’s the Difference?

Pityriasis rosea is a skin disease that usually lasts for a limited period of time. According to Cleveland Clinic, this condition is 50 percent more likely to affect women and most often develops from ages 10 to 35. Anyone can develop pityriasis rosea, however.

Psoriasis, on the other hand, is often a chronic (ongoing) condition. It is lifelong, although treatments can help keep symptoms under control. It, too, can affect anyone, but according to the American Academy of Dermatology Association, white people are diagnosed more often than those of other races or ethnicities.

Symptoms of Pityriasis Rosea and Psoriasis

Both pityriasis rosea and psoriasis can lead to a discolored, scaly rash, although the symptoms may look different, last for different lengths of time, and affect different areas of the body.

Pityriasis Rosea Symptoms

Pityriasis rosea often starts with symptoms outside the skin, including:

• Tiredness
• Fever
• Sore throat
• Headache
• Stuffy nose or other symptoms of an upper respiratory infection (such as sinusitis or the common cold)

Next, a rash may appear, starting with one patch of affected skin — the herald patch — followed by multiple patches. These patches are usually raised and scaly and may be pink, red, purple, brown, gray, or black. The affected areas are itchy for about half of the people but don’t usually hurt.

A pityriasis rosea rash most often appears on a person’s trunk — the chest, back, or stomach. The shape of the rash can resemble that of a Christmas tree, which is why pityriasis rosea is sometimes called Christmas tree rash. Scaly spots sometimes also show up on the neck, arms, or legs. For 4 out of 5 people with pityriasis rosea, the rash disappears within one to three months.

Psoriasis Symptoms

There are a few types of psoriasis, which may lead to different symptoms. They include:

• Plaque psoriasis — Thickened, scaly patches that often form on the elbows, knees, lower back, or scalp
• Guttate psoriasis — Tiny, scaly, pink bumps on the arms, legs, or torso that can resemble pityriasis rosea
• Inverse psoriasis — Smooth, reddened patches that form in the armpits, buttocks, genitals, or other locations where skin rubs together
• Pustular psoriasis — Inflamed skin with bumps that look like pimples

Psoriasis patches often itch, and sometimes they’re painful.

Psoriasis can also lead to symptoms in other parts of the body. It may cause silvery scales on the scalp, or discoloration, roughness, pitting, or denting of the fingernails or toenails. Some people with psoriasis also develop psoriatic arthritis, which leads to pain and swelling in the joints.

Plaque psoriasis — the most common form of the condition — typically lasts for the long term. Other types, such as guttate psoriasis, may disappear in a few weeks or months. However, sometimes guttate psoriasis persists for life.

Causes of Pityriasis Rosea vs. Psoriasis

Each of these conditions likely involves the immune system, but they may be triggered by different factors.

Researchers don’t know for sure what causes pityriasis rosea, although many believe that it’s caused by a virus in the herpes family. This may be why the symptoms are the same as those of a respiratory infection. However, pityriasis rosea isn’t contagious.

Psoriasis occurs when the immune system mistakenly attacks skin tissue. Several factors may trigger psoriasis, including:

• Infections
• Injury
• Stress
• Heavy drinking
• Cigarette smoking
• Certain medications

This condition can also run in families and is likely influenced by genetics. Like pityriasis rosea, psoriasis can’t be spread from person to person.

Diagnosis of Skin Conditions

It can be hard to tell pityriasis rosea and psoriasis apart, and these skin disorders may also be mistaken for other conditions.

For example, pityriasis rosea can look very similar to eczema (a condition that causes itchy, inflamed skin) or ringworm (a fungal infection that produces a circular red rash). Some medications, such as bismuth (Pepto Bismol), interferon, and the blood pressure medication clonidine (Catapres), can cause a pityriasis rosea-like rash as a side effect. Psoriasis, too, can be confused with a variety of different skin conditions, including eczema, lupus, syphilis, and lymphoma.

To diagnose skin issues, a doctor or dermatologist (specialist in skin conditions) will look closely at the skin. They may ask if any skin disorders run in your family and ask for details about symptoms.

Doctors typically use certain tests to gather more information. Allergy tests may help identify whether a rash is part of an allergic reaction, while blood tests can look for other health issues that could cause skin changes. During a biopsy, a doctor may remove a small sample of skin for further study under a microscope.

If a doctor suspects psoriasis, they may also look more closely for problems with the nails, scalp, or joints to diagnose the condition.

Treatment Options for Pityriasis Rosea and Psoriasis

Doctors typically recommend different treatments for pityriasis rosea and psoriasis, although some therapies may help with both conditions.

Pityriasis Rosea Treatments

Treatment isn’t always needed for pityriasis rosea, as the condition may disappear on its own. If the rash itches, antihistamines (allergy drugs), calamine lotion, and corticosteroids may help bring relief. These medications are often topical — applied to the skin in a cream or an ointment. Steroids may also be given orally as pills or tablets.

Because pityriasis rosea is thought to be caused by an infection, some doctors recommend taking antiviral drugs such as acyclovir or antibiotics. However, it’s unclear whether these medications actually treat the condition.

Phototherapy or light therapy — exposing the skin to ultraviolet (UV) light — can sometimes help clear pityriasis rosea. In this case, a limited amount of sunlight may help.

Psoriasis Treatments

Psoriasis treatment options vary based on a person’s age, overall health, type of psoriasis, and the location and severity of symptoms. Therapy typically requires more extensive treatments than those for pityriasis rosea.

Many psoriasis treatments are topical creams or ointments. Topical treatments include:

• Corticosteroids
• Vitamin D
• Retinoids (forms of vitamin A)
• Salicylic acid
• Tapinarof cream

People with more severe psoriasis may also need other medications that are injected or taken by mouth. Injected and oral drugs include:

• Steroids
• Retinoids
• Biologics (medications developed from proteins, blood, or other natural sources)
• Immunosuppressants (drugs that calm the immune system)

Phototherapy can also be a useful psoriasis treatment because sunlight or UV light helps clear the skin. In some cases, light treatments may be given along with medications that make the skin more sensitive to sunlight.

Unlike pityriasis rosea, psoriasis can affect parts of the body besides the skin. These extra symptoms may require other treatments. For example, scalp psoriasis, which can cause fine scales in the hair that look like dandruff, may be treated with a medicated shampoo. Nail psoriasis may require aggressive topical treatments.

Deciding on a Treatment Plan

If you develop a new or worsening rash, get in touch with your health care team. Your doctor can help you figure out whether you may have pityriasis rosea, psoriasis, or another skin condition. They can also recommend suitable treatments.

If your current treatment plan isn’t working well, ask your doctor about trying a different option that may do more to control your symptoms and provide you with a better quality of life.

Talk With Others Who Understand

On MyPsoriasisTeam, the social network for people with psoriasis and their loved ones, more than 116,000 members come together to ask questions, give advice, and share their stories with others who understand life with psoriasis.

Have you been diagnosed with pityriasis rosea or psoriasis? Was it difficult to get a correct diagnosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.