What is psoriasis?

Psoriasis is a lifelong disease of the immune system that affects the skin. Psoriasis is an inflammatory skin condition that most commonly causes red skin patches, often covered with thick, silver, flaky scales, which form in areas where new skin cells grow faster than normal. Inflammation, pain, and itching can occur.

Do you think that you or someone you know may have psoriasis? If so, it could be one or more of the following 5 types of psoriasis: plaque psoriasis, guttate psoriasis, pustular psoriasis, erythrodermic psoriasis, and inverse psoriasis.

Read our article "What is psoriasis?" to learn more about the different types of psoriasis.

What causes psoriasis and who is at risk?

The cause of psoriasis is not clear. One theory among researchers is that certain cells in the immune system called T cells are triggered and become overactive.

This T cell activity causes inflammation, and the outer layer of skin cells is shed but is replaced much faster than normal – in about 3 to 5 days instead of the usual 28 to 30 days. Since skin cells grow more quickly than they can be shed, they build up on the outer layer of skin, to form the characteristic scales.

Experts believe that the immune system is triggered by certain factors to cause psoriasis symptoms. Psoriasis triggers may include:

  • skin injury, including sunburn
  • respiratory infection caused by bacteria or viruses
  • medications, including certain heart medications (e.g., beta-blockers such as metoprolol or ACE inhibitors such as ramipril), indomethacin, lithium, anti-malaria medications (e.g., chloroquine), and oral corticosteroids (if overused or stopped abruptly). If you are taking any of these, do not stop or change the way you are taking your medications until you talk to your health care provider.
  • stress
  • alcohol
  • smoking
  • cold weather
  • hormones

Psoriasis affects about one million Canadians. It usually appears between the ages of 15 and 35, although it may occur at any age. Men and women are equally affected, and people of all races are affected.

There may be a genetic component to psoriasis, so family history is an important risk factor for psoriasis. If you speak to your doctor about psoriasis, be sure to mention any family members who have also had skin conditions.

It is important to note that psoriasis is not contagious and can't be spread to others.

What are the symptoms of psoriasis?

There are different types of psoriasis. Psoriasis is characterized by lesions on the skin. Often, the lesions appear symmetrically (the same place on both sides of the body). The lesions can be painful and itchy. Depending on the type of psoriasis, the lesions can have a different appearance and vary in size.

Plaque psoriasis, the most common type of psoriasis, causes lesions that are usually well-defined, red, raised plaques covered with silvery, shiny scales. The lesions may appear anywhere but are usually found on the knees, elbows, scalp (scalp psoriasis), and torso. They can also be found on skin folds, nails (nail psoriasis), face, palms, and soles of the feet. Nail psoriasis symptoms include thickened, discoloured, pitted, and splintered nails.

Psoriasis symptoms can be severe. Plaque psoriasis is considered severe when 10% or more of the body is affected.

If you have been diagnosed with psoriasis, your doctor may use a questionnaire called the DLQI (Dermatology Life Quality Index) to assess how well you are responding to the current treatment plan and to find the most satisfactory option for your condition.

About 30% of the time, people with psoriasis also suffer from a type of arthritis (joint inflammation, pain, and stiffness) called psoriatic arthritis.

When you have psoriasis, you will always have it, but symptoms can flare up and then disappear for periods of time. Symptoms range from mild to severe.

Living with psoriasis

Since psoriasis and its skin lesions are visible to others, it's to be expected that you might feel stress or some degree of social stigma, or even have poor self-esteem.

Psoriasis is not merely a cosmetic condition. Psoriasis can have a huge impact on your quality of life in general and on how you feel in your relationships, work, and school in particular.

The good news is that psoriasis can be effectively treated and managed. Treating psoriasis can help improve your quality of life. Learn more about treatment.

Effective psoriasis treatment varies from person to person. Finding the right choice for yourself may take several tries and will require close collaboration between yourself and your doctors and nurse practitioners. Various treatment options can have different advantages and disadvantages; the best choice will maximize the benefit while minimizing the risks. You should also consider the impact of the treatment on your quality of life.