Psoriasis is a common chronic inflammatory skin condition that involves red elevated patches and flaking silvery scales. It can take on several different forms and appearances, and symptoms can range from mild to severe.

Signs and symptoms

The lesions can be painful and/or itchy and vary in size. Since plaques consist of dry, flaky inflamed skin, it may also crack and bleed. While lesions can appear anywhere on the body, the most common sites include elbows, knees, scalp, chest and lower back. The plaques tend to appear in the same place on both sides of the body.

Who is at risk?

Psoriasis can develop at any age, although it is typically seen in adults. One form of psoriasis called guttate psoriasis tends to occur in childhood and early adulthood. Psoriasis occurs equally among men and women and across different races. Family history of psoriasis is a leading risk factor. In recent years, research has been discovering some of the genes involved in psoriasis.

What causes it?

While it is not known exactly what causes psoriasis to develop in certain individuals, experts believe that the condition may involve malfunctioning of the immune system and the consequent production of inflammation. White blood cells (T cells) in the immune system are triggered and this causes inflammation to occur, which then causes skin cells to rise to the surface and shed at an abnormally quick rate. Skin cells shed every 3 to 4 days in psoriasis whereas in normal healthy skin, the skin cells turnover cycle is typically 30 days.

Despite being labelled as a skin disease, psoriasis has an impact on patients that extends beyond the cosmetic or physical aspects. It negatively affects quality of life from the burden of physical pain, discomfort and limitations to exacting a heavy emotional toll. According to a national patient survey, psoriasis and related conditions “impose a sever burden on the daily lives of Canadians with a history of moderate to severe psoriasis.” Over one third of respondents (176 of 500) viewed their skin condition as a significant problem in their daily life. The perception seemed to correlate with the extent of disease or how much of their body surface psoriasis affected. People with psoriasis have an increased risk of depression, anxiety and suicide.

Psoriatic lesions can be itchy, painful and bleed, making it difficult to sleep, dress or engage in various daily activities. If there is joint involvement, the pain can also make it challenging for the individual to function physically.

In terms of physical and mental disability, psoriasis has been compared to having cancer, arthritis, hypertension, heart disease, diabetes, and depression. The quality of life is the major concern. The aim of treatment is ultimately to reach an appropriate quality of life.

Quick facts about psoriasis
  • Psoriasis affects 1 million Canadians and 125 million people worldwide.
  • The most common form is plaque psoriasis, which affects approximately 90% of patients.
  • Psoriasis often causes as much disability as cancer, diabetes and other major medical diseases.
  • Up to 30% of patients with psoriasis have or will have arthritis and 5–10% may have some functional disability from arthritis of various joints.
  • Having psoriasis may increase the risk of developing other chronic systemic diseases, including heart attack and stroke, diabetes, cancer, liver disease and other serious health conditions.

Psoriasis can take on a variety of forms, which include plaque, guttate, pustular, inverse and erthyrodermic. Some of these types may evolve from plaque psoriasis.

Plaque psoriasis is the most common form and it occurs in about 90% of patients.It usually begins with red scaly patches.The symptoms can range from mild to severe, covering very small or extensive areas of the body.Psoriasis is severe when 10%or more of the body surface is affected by psoriasis.

Guttate psoriasis is typically of abrupt onset, appearing in a few weeks, being often quite extensive. It is marked by lesions that are small and “drop-like”, which often appear on the trunk (i.e. lower back), arms, legs or scalp. It makes up about 10% of psoriasis cases and is the second most common form. It often develops following an upper respiratory infection, namely strep throat, which acts as the trigger. Guttate psoriasis can resolve on its own without treatment, and the individual will never develop psoriasis again, or it can become recurrent throughout life. Sometimes, it can become severe and require treatment.

Pustular psoriasis is characterized by pus-filled pustules. It can be limited to certain areas of the body (localized) or widespread (generalized). If localized, the pustules are usually confined to the palms and soles of the feet. Scales gradually form as pustular lesions dry out.

Inverse psoriasis occurs in skin folds (also called “flexures”) where there tends to be pressure, friction and/or moisture or perspiration, such as between buttocks, the genitals, under breasts and armpits. These lesions are smooth and red as opposed to raised and scaling.

Erythrodermic psoriasis is a rare but serious form of disease marked primarily by widespread redness and inflammation that resembles sunburn. It can result from severe sunburn, using certain medications (i.e. oral corticosteroids, lithium) or even suddenly stopping psoriasis treatment. It can also stem from poorly controlled psoriasis. It can be life-threatening and usually requires hospitalization, since the skin loses its ability to perform vital functions, such as controlling body temperature and protecting against infectious organisms (i.e. bacteria).

Psoriatic arthritis
This form of psoriasis, often seen as a disease in its own right, may be severe and involves inflammation, stiffness and pain within joints (arthritis) in addition to skin plaques. Psoriatic arthritis may affect up to one third of patients with psoriasis. The skin plaques and joint pain do not coincide, so a flare-up may consist of joint pain in the absence of visible lesions or vice-versa. Typically, the arthritic component develops about a decade after the skin plaques.

For more information

CDA-reviewed patient information is available at Accurate medical information can also be found on the American Academy of Dermatology website at PsoriasisNet, the US National Psoriasis Foundation website and the New Zealand Dermatological Society website.

Psoriasis may be permanent or episodic, meaning that it can flare up then subside and disappear altogether for a while before another episode occurs. Triggers or precipitating factors may cause a flare-up in disease or even lead to the development of psoriasis, such as emotional stress, local injury to skin, systemic infections, and the use of certain medications.

Infection such as upper respiratory bacteria or viruses can actually cause someone to develop psoriasis. For example, psoriasis may first appear a few days after one develops strep throat.

Skin injury or any break in the skin can lead to psoriasis. This can include a razor nick or burn, an insect bite, cut, abrasion, sunburn, needle puncture (from vaccination), blister or bruise. Patients often find that new lesions appear at the site of injury.

Medications such as lithium (antidepressant) can also predispose one to a flare-up or cause psoriasis to first appear. Other drugs that can trigger psoriasis or aggravate it include anti-malarials, beta blockers (a type of high blood pressure medication) and an arthritis drug called indomethacin. Even oral corticosteroids can worsen psoriasis symptoms with overuse or if treatment is stopped abruptly.

Stress is a factor in a number of health conditions and seems to be a trigger for psoriasis as well. It can worsen symptoms and, in some cases, a stressful event may trigger the onset of psoriasis. Living with psoriasis also contributes to stress, which in turn, can negatively affect the skin condition.

Weather is another factor that can cause psoriasis to improve or worsen. In particular, the dry cold winter season seems to adversely impact on psoriasis because it dries and irritates the skin. Sun helps psoriatic plaques to fade which suggests why UV light therapy is often used to help treat psoriasis.

Hormones are suspected since puberty can often coincide with the onset of psoriasis symptoms, while pregnancy has been shown to improve or worse psoriasis, depending on the individual.

Other factors that science is sussing out include smoking and heavy alcohol use. Studies have found that people who smoke run a much higher risk of developing psoriasis compared to non-smokers. The same goes for people who drink heavily. Both smoking and alcohol use also seem to interfere with treatment success and disease remission.

Q: Is psoriasis contagious through touching?
A: No, psoriasis is not contagious. It is not an infectious disease.
Q: Will treatment make psoriasis go away permanently?
A: Sometimes, if treatment is effective, it can send psoriasis into remission, making symptoms disappear for weeks or months at a time.
Q: Is it possible to prevent psoriasis?
A: If you have a family history, you can help to prevent or minimize the chances of developing psoriasis by reducing stress, avoiding skin irritation and injury, and discussing with your physician any medications you take.
Q: What happens if I stop treatment?
A: Stopping treatment abruptly, such as corticosteroids, can actually trigger a more severe form of psoriasis.
Q: Can I have more than one type of psoriasis?
A: An individual can have different forms of psoriasis appearing at once or at different times.

There are several treatments available to help manage psoriasis. Determining the most appropriate treatment is very individual and based on the type and severity of disease, how large or widespread plaques are, on what the patient agrees to use based on benefits and risks and how well a patient responds to a given treatment. A physician may change a patient’s treatment dose, combine one kind of therapy with another, or switch treatments if one doesn’t work for a patient.


Topically applied treatments, such as creams and ointments, are usually recommended first, particularly for mild psoriasis. The aim of this kind of treatment is primarily to slow down and regulate skin cell turnover, reduce inflammation and suppress the immune system. These options include topical corticosteroids, topical derivatives of vitamin D (calcitriol and calcipotriol), topical derivatives of vitamin A (tazarotene), and coal tar. Physicians may recommend a combination of these topical agents or combine them with oral and/or light therapy.


A number of oral drugs can help to manage psoriasis and are usually reserved for the treatment of more severe and/or widespread symptoms. Traditional systemic treatments are methotrexate, also used to treat arthritis, acitretine, used for psoriasis only and cyclosporine, a potent immunosuppressive agent to be used only for short periods. In addition to these traditional drugs, novel agents such as biologic response modifiers (or biologics), can be given by injection or infusion. Many biologics are now available: alefacept, etanercept, adalimumab, infliximab, ustekinumab. Ongoing research will also bring new options. Systemic treatments work generally by helping to regulate and normalize skin cell turnover and suppressing the immune response that causes inflammation and plaques.

Light therapy

Both natural and artificial ultraviolet (UV) light are used to treat psoriasis. Many patients with psoriasis find that sunlight exposure seems to improve their skin symptoms. However, sunburn can worsen the condition, which is why only a modest amount of exposure is recommended. One form of light therapy is Narrow Band UVB phototherapy, which emits a short wavelength of UV light that penetrates the epidermis or outermost layer of skin. Another form of light therapy is psoralen and UVA (PUVA), which combines an oral or topical form of the drug, psoralen, and UVA light exposure. The drug makes the skin more sensitive to the UVA light, helping it to work better.

Combination therapy

There are many treatment options for patients with psoriasis. The challenge for both physician and patient is to find what works most effectively for the individual. In many cases, a physician may choose to combine 2 or more treatments for the best outcome.