What Causes Psoriasis and Is It Contagious?

Medically reviewed by Debra Sullivan, PhD, MSN, CNE, COI on August 3, 2016Written by Annette McDermott on August 3, 2016

The basics

Psoriasis is an autoimmune disorder characterized by inflamed areas of skin. Approximately 7.5 million people in the United States are affected by psoriasis. People with the most common type of psoriasis, plaque psoriasis, develop thick patches of red and white scaly skin known as lesions. These lesions may appear anywhere on the body. They typically show up on the elbows, knees, and scalp.

You may be wondering whether these lesions are contagious. For example, it is possible to transmit the skin condition to someone else if they touch one of these lesions? Keep reading to learn more about what can cause psoriasis and how to reduce your risk of flare-ups.

Is psoriasis contagious?

Psoriasis is never contagious. Unlike some other skin conditions such as scabies, impetigo, and MRSA, psoriasis isn’t caused by contagious bacteria or another type of infection. Psoriasis is an autoimmune disorder. According to the American Academy of Dermatology, you must have specific genes to develop the disease. If you do have these genes, environmental triggers generally activate this condition.

Five different types of psoriasis exist. Each type has a unique rash which may resemble contagious skin conditions:

  • Plaque psoriasis causes red, raised patches of skin. These patches are typically covered by a silvery buildup of scaling or dead skin cells.
  • Guttate psoriasis causes small red spots all over the skin. It often happens after an illness or infection, such as strep throat.
  • Pustular psoriasis causes painful, raised, pus-filled bumps on the palms and soles that may itch. Pustular psoriasis may also cause flulike symptoms, such as fever, chills, and a loss of appetite.
  • Inverse psoriasis causes sore, red patches of skin. It usually occurs in the skin folds.

Erythrodermic psoriasis

This condition causes the skin to become bright red. It resembles a severe, all-over sunburn. The body can’t maintain its temperature and may cause rapid heart rate, intense pain, and intense itching. Erythrodermic psoriasis is an emergency condition.

How do you develop psoriasis?

The exact cause of psoriasis isn’t fully understood. It’s thought that overactive T cells, which are cells that fight off viruses and bacteria in your body, are involved. In people with psoriasis, T cells attack healthy skin cells and activate other immune responses. This increases the production of healthy skin cells, T cells, and other white blood cells.

As a result, too many skin cells accumulate on the skin’s outer layer. This is why some types of psoriasis cause the skin to have a scaly appearance. It normally takes weeks for new skin cells to form. In people with psoriasis, skin cells form within days. The body doesn’t shed the excess cells, and psoriasis lesions occur.

What triggers a psoriasis flare?

Many environmental and lifestyle factors may trigger psoriasis flares. Not everyone with psoriasis has the same triggers. Common triggers are:

  • sun exposure
  • smoking
  • infections
  • skin trauma, such as cuts, bug bites, and burns
  • stress
  • exposure to cold temperatures
  • certain medications, such as lithium, blood pressure medications, and iodides
  • heavy alcohol use

Smoking isn’t just a psoriasis trigger. It may also be involved in its development and increase the severity of the disease. Research shows smoking may cause 1 in 5 cases of psoriasis and doubles your risk of getting the condition. This may be due to the effects of nicotine on skin cells, skin inflammation, and your immune system.

Although some say that allergies and certain foods can trigger psoriasis flares, these claims are mostly anecdotal.

Check out: Psoriasis by the numbers: Facts, statistics, and you »

When is psoriasis typically diagnosed?

According to the National Psoriasis Foundation, psoriasis often develops between the ages of 10 and 35. It may appear at any age, though. Up to 15 percent of people with psoriasis are diagnosed before age 10. In rare cases, infants can develop the condition.

Dermatologists usually diagnose psoriasis, although many primary care physicians will recognize it. Most doctors diagnose psoriasis by performing a visual skin exam and assessing family medical history. You’re considered at risk of developing psoriasis if you have one parent with the disease. If you have two parents with psoriasis, this risk is higher. In some cases, a doctor can perform a skin biopsy to confirm the diagnosis and the type of psoriasis you have.

No cure for psoriasis is available. The disease may go into remission, however. The goal of psoriasis treatments is to slow the growth of skin cells, reduce inflammation and scaling, and smooth the skin. You may be able to accomplish this through medication, topical treatments, and light therapy.

The bottom line

Psoriasis isn’t contagious in any form. It’s an autoimmune condition, not an infectious disease. If you hear someone question that fact, take a moment to educate them. Doing so can help promote an environment of acceptance and understanding.

The results of a 2003 survey conducted by a program called “Beyond Psoriasis: The Person Behind the Patient,” reinforce why psoriasis education is so important. Seventy-three percent of people with severe psoriasis and 48 percent of people with moderate disease reported low self-confidence. Sixty-four percent of respondents said the public is afraid psoriasis is contagious. Forty-five percent said people with psoriasis are ridiculed. With this in mind, it’s that much more important to educate yourself and others about the causes and symptoms of the condition.

Keep reading: 9 Psoriasis myths you probably think are true »

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