What is Psoriasis? 

Psoriasis (pronounced so-RYE-a-sis) is a chronic inflammatory condition that affects the regeneration of skin cells.

Normal skin cells grow, mature and are shed as part of a natural cycle that takes 28 to 30 days. Psoriasis is a common skin condition that happens when faulty signals in the body’s immune system trigger new skin cells to form in three to four days instead. Because the skin cells grow too quickly, they are not shed normally. Instead, they pile up on the skin’s surface, creating sores or lesions – often called plaques. Thick, silvery scales form atop these itchy and sometimes painful red patches.

Psoriasis usually affects the elbows, knees and scalp, but it can also occur on the palms of the hands, soles of the feet, nails, genitals and torso.

If you suspect that you might have psoriasis or if you’ve received a formal diagnosis, you can take some comfort in knowing that you’re not alone. Nearly a million Canadians are affected by psoriasis.

Psoriasis is a persistent, chronic condition that may come and go – flare up then go into remission.

During flare-ups, psoriasis causes itchiness and pain in the inflamed skin. Under this stress, the skin may crack and bleed. There is no cure for psoriasis, but treatment can interrupt the psoriasis cycle and significantly relieve its symptoms and appearance.

Psoriasis can range from a few dandruff-like scales to widespread patches that cover large areas of skin. For many people, psoriasis is nothing more than a nuisance. For others, it’s an embarrassment. And for a few, it’s a painful and disabling condition.

Risk Factors

No one knows what causes psoriasis, but genetics may play a major role in its development, as psoriasis often runs in families. About one in three people with psoriasis has a close relative with this condition.

People with certain medical conditions, such as HIV, are more likely to develop psoriasis. Other risk factors are:

  • Family history
  • Stress
  • Obesity
  • Smoking
  • Heavy alcohol intake


Flares of psoriasis are often linked to triggers – factors in the environment that set off the faulty immune response that causes psoriasis. Everyone’s triggers are different, but common triggers include:

  • Cold or dry climate
  • Infections
  • Stress
  • Dry skin
  • Certain medications, e.g., non-steroidal anti-inflammatory drugs (NSAIDs), high-blood-pressure medications, some antidepressants, anti-malarial drugs and others
  • Skin injuries, including sunburn, cuts and bug bites

Different Levels of Severity

Severity of psoriasis varies with each person and can range from a few patches here and there to full body involvement. Assessment is usually discussed in terms of “mild,” “moderate” and “severe.” In psoriasis patients, about 65% of people have mild psoriasis, about 25% have moderate psoriasis, and about 10% have severe psoriasis.

Mild psoriasis

  • Covers less than 3% of the body*
  • Generally involves isolated patches on the knees, elbows, scalp, hands and feet
  • Little effect on the quality of life

Moderate psoriasis

  • Covers 3% to 10% of the body*
  • Generally appears on the arms, torso, scalp and other regions
  • Often results in concern about others’ reaction to visible lesions
  • Affects the quality of life

Severe psoriasis

  • Covers more than 10% of the body*
  • May affect large areas of skin
  • Psoriasis of the face and palms/soles may be considered as severe
  • Severe impact on the quality of life

To assess the area of involvement, consider that your palm covers about 1% of the skin’s surface; the number of palms of your skin involved with psoriasis is a reflection of the body surface involved.

*National Psoriasis Foundation

The Emotional Impact

The emotional impact of psoriasis on a person’s life does not depend on the severity of the lesions. It is determined by how each person feels about the itchiness, pain and discomfort of psoriasis and the visibility of the lesions.

  • Psoriasis is associated with a lack of self-esteem, sexual dysfunction, anxiety and depression
  • Up to 60% of people with psoriasis may develop depression  
    • Biologic therapy may lessen the symptoms of depression o
    • Depression is treatable with antidepressant medication, such as serotonin re-uptake inhibitors (SSRIs)

Fast Facts about Psoriasis

  • Psoriasis often begins between the ages of 15 and 25, but it can happen at any age.
  • Psoriasis affects men and women nearly equally.
  • Psoriasis is not contagious; it cannot be spread from one person to another. The lesions can become infected, if scratched, but they are not infectious.
  • Personality has nothing to do with psoriasis; it can happen to anyone. Psoriasis affects people of all sexes, races and ethnic groups.
  • Psoriasis cycles from better to worse to better and so on. Outbreaks may come and go. Psoriasis may also persist for long periods without getting better or worse.
  • About 2% to 3% of the world’s population has psoriasis (World Health Organization).
  • Nearly 60% of people with psoriasis report that psoriasis is a problem in daily life.
  • About 30% of people who have psoriasis will get psoriatic arthritis, a type of inflammatory arthritis.
  • Because psoriasis is a visible skin condition, it can affect people’s feelings, behaviour and experiences.
  • About 60% of people with psoriasis miss an average of 26 days of work each year because of their condition.
  • One of every 3 people with psoriasis has a family member with psoriasis.