What is psoriasis?

What is psoriasis, exactly? Let's start with what it's not. It is not contagious. That means you cannot get psoriasis from another person. And, it is not just a skin condition. Psoriasis is a lifelong condition of the immune system. The exact cause is unknown; however, researchers think that family history, environment, and the immune system can all play a role in psoriasis.

What’s happening inside your body?

Normally, skin cells that form in the deepest layers of your skin make their way to the surface of your skin. They then flake off and are replaced with new skin cells. This takes about a month.

Plaque psoriasis on knees
An example of plaque psoriasis on knees

However, in people with psoriasis, the immune system sends signals that make skin cells grow faster than normal. Cells move to the surface of the skin in about four days. Since they move so quickly, they don't have time to fully mature and flake off. In plaque psoriasis, which is the most common type of psoriasis, the cells collect on the skin’s surface, forming raised, red patches known as plaques. They often have silvery scales.

While plaque psoriasis is the most common, there are other types of psoriasis that can affect different areas of the body and appear in a variety of forms. Symptoms may appear on any part of your body, including your hands, feet, scalp, and nails. Some people may also feel pain in their joints, stiffness in the morning, or tiredness. If you have any of these joint symptoms, you may have a related condition called psoriatic arthritis.

See pictures of psoriasis

If you have psoriasis, you're not alone. Up to 7.5 million adults in the United States have psoriasis. It affects men and women at equal rates, and it affects people of all ages. Sign up for emails to learn more about psoriasis and a treatment option.

How severe is your psoriasis?

The severity of psoriasis is based on how much of your body has plaques on it, and how your psoriasis affects your life. Your doctor will assess your symptoms, but you can use this quick guide to help you get an idea of how severe your psoriasis may be. About 1 out of 5 people with psoriasis have plaque psoriasis with symptoms that are moderate to severe.

Psoriasis severity chart
  • Psoriasis is not contagious
  • Psoriasis is a condition of the immune system
  • The severity of psoriasis is based on how it affects you and how much of your body is covered
  • About 1 in 5 people with psoriasis have moderate to severe plaque psoriasis
Did you know?
About 80% of people with psoriasis have plaque psoriasis.