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 features. This can make it difficult to figure out what’s causing a new rash. For example, a psoriasis rash can sometimes resemble the rash seen with 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 healthcare provider. This is more effective 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 said, “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. Anyone can develop the condition, but it’s 50 percent more likely to affect women, according to Cleveland Clinic. It most often develops from ages 10 to 35.

Psoriasis, on the other hand, is often a chronic (ongoing) condition. It’s lifelong, but treatments can help keep symptoms under control. According to the American Academy of Dermatology, most people with psoriasis have white skin, but the condition affects people of all racial backgrounds. Some research suggests the condition may be underdiagnosed in people who are Black, Hispanic, or Asian, according to the Psoriasis Foundation.

Symptoms of Pityriasis Rosea and Psoriasis

Both pityriasis rosea and psoriasis can lead to a discolored, scaly rash. But 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, known as the herald patch. It’s then 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. For that reason, pityriasis rosea is sometimes called Christmas tree rash. Scaly patches sometimes also appear 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, discolored bumps on the arms, legs, or torso that can resemble pityriasis rosea
• Inverse psoriasis — Smooth, discolored 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 can sometimes be 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 lasts 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. Many believe that it’s caused by a virus. This may be why the symptoms are similar to 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 to flare, including:

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

This condition can also run in families and is likely influenced by genetics. Also, neither condition is contagious.

Diagnosis of Skin Conditions

It can be hard to tell pityriasis rosea and psoriasis apart. Plus, these skin disorders may 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 rash). Some medications, such as bismuth, interferon, and the blood pressure medication clonidine, can cause a rash resembling pityriasis rosea as a side effect. Psoriasis, too, can be confused with a variety of skin conditions, including eczema, lupus, syphilis, and lymphoma.

To diagnose skin issues, a dermatologist 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. 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. However, 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 an antiviral drug such as acyclovir. Research suggests it might help relieve symptoms or speed healing in some cases, but it’s not considered a primary treatment.

Phototherapy (light therapy) — exposing 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 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
• Coal tar
• Salicylic acid
• Tapinarof cream

People with more severe psoriasis may also need other medications that are injected or taken by mouth. Oral and injected drugs for psoriasis 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 can sometimes help 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 healthcare 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 134,000 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, start a conversation by posting on your Activities page, or connect with like-minded members in Groups.