Psoriasis: what you need to know
What is psoriasis?
Psoriasis is a common skin condition, usually characterised by red, scaly patches that may be sore or itchy. The patches occur most commonly on the knees, elbows, lower back and scalp, although the skin can be affected anywhere on the body. The nails may also be involved, and a small number of people also get pain and swelling of the joints (psoriatic arthritis).
Psoriasis is a chronic (ongoing) condition. Although people of any age can be affected, the most common age for psoriasis to start is late teens to early adulthood.
Although there is no cure for psoriasis, there are treatments available in Australia that can control the symptoms.
The symptoms of psoriasis vary between people and also at different times - there may be times when symptoms improve or disappear (remission) and other times when symptoms worsen.
- red patches of skin covered with white or silvery scales;
- skin soreness or itch;
- dry, cracked skin;
- nail ridges, pitting and discolouration of nails; and
- painful, swollen and stiff joints (in a small proportion of people) - known as psoriatic arthritis.
Types of psoriasis
There are different types of psoriasis, the most common being chronic plaque psoriasis, which tends to affect the knees, elbows, lower back and scalp.
Other less common types include:
- inverse (flexural) psoriasis, which affects areas such as the armpits and groin;
- palmoplantar psoriasis, which affects the hands and feet;
- guttate psoriasis, which usually affects children and young adults and often develops after an infection;
- pustular psoriasis - a rare form of psoriasis that can be severe and involves pus-filled blisters; and
- erythrodermic psoriasis, which is a rare, severe form of psoriasis that involves most skin on the body.
What causes psoriasis?
The exact cause is not known, but the immune system is known to be overactive in people with psoriasis. A type of immune cell known as a T cell attacks healthy skin, triggering the skin cells to turn over at a faster rate than normal (in days instead of weeks). This leads to thickening of the skin and shedding as scales.
The condition tends to run in families, so inherited factors have an important part to play. Also, certain environmental factors may trigger the development of psoriasis.
Factors that may trigger psoriasis or make it worse (flare up) include:
- infections (e.g. streptococcal throat infections, viral infections and thrush);
- damage to the skin from trauma such as a bad graze, cut or sunburn;
- hormonal changes (e.g. during puberty, pregnancy or menopause);
- certain medicines (e.g. lithium, which is prescribed for bipolar disorder, beta-blockers, and some antimalarial medicines);
- suddenly stopping corticosteroid medicines;
- heavy alcohol intake; and
Psoriasis is not contagious - it cannot be passed from one person to another.
Other conditions associated with psoriasis
Having psoriasis may also increase your risk of certain other health problems, including:
- Crohn’s disease (a type of inflammatory bowel disease);
- type 2 diabetes;
- some eye conditions, including conjunctivitis;
- cardiovascular disease (including coronary heart disease and stroke);
- depression; and
Tests and diagnosis
Psoriasis can usually be diagnosed based on symptoms and the appearance of the skin and nails. In some cases, a biopsy (where a small sample of affected skin is removed and examined under a microscope) may be recommended to confirm the diagnosis.
Your doctor may refer you to a dermatologist (skin specialist) for biopsy or treatment. If your joints are affected, you may also need to see a rheumatologist (specialist in conditions affecting the joints).
Although there is no cure for psoriasis, in most cases the disease can be well controlled.
Various treatments are available for psoriasis, depending on its severity and the areas of skin involved. There is no single treatment that suits everyone. It may be necessary to rotate through a series of different treatments, or use a combination of treatments to get the best control.
Topical treatments for psoriasis
Some people with very mild disease may need only over-the-counter topical treatments (treatments applied directly to the skin or scalp). These include:
- emollients (moisturisers), applied daily to help with scaling and itching;
- special medicated shampoos that may contain keratolytics (such as salicylic acid) that soften and remove scale; and
- bath oils.
Topical treatments that doctors may prescribe include ointments, creams or shampoos containing:
- corticosteroids, which reduce inflammation and skin cell production;
- tar (coal tar or ichthammol), which reduces inflammation, scaling and itching; and
- calcipotriol (brand name Daivonex Cream), a vitamin D-based medicine that slows skin cell growth.
Calcipotriol and corticosteroids are usually given together, and there are combination preparations available.
Less commonly, dermatologists may recommend:
- tazarotene (e.g. Zorac Cream), a vitamin A-based medicine that may ease inflammation; or
- dithranol, which can help control production of skin cells but is now rarely used.
For people whose disease isn’t controlled by topical therapies alone or who have quite widespread disease, another treatment option is ultraviolet light therapy (phototherapy). Phototherapy reduces inflammation and inhibits the immune response in the skin.
Artificial UV light therapy requires specialist supervision, so it is mainly available through hospitals or some dermatologists' practices.
You may also find that regular exposure to sunlight for short periods helps your psoriasis. Ask your doctor about the amount of sunlight that is safe, as excessive sun exposure can trigger symptoms and also cause sunburn and skin damage.
Treatments for severe psoriasis
Other treatment options for those people with more severe disease include oral medicines such as:
- methotrexate (taken once per week to suppress the immune system, control inflammation and reduce skin cell production);
- acitretin (brand names include Neotigason, Novatin), a vitamin A-based medicine that can help reduce skin cell production and inflammation); and
- cyclosporin (e.g. Cicloral and Neoral), which suppresses the immune system.
While generally effective, these medicines can have potentially serious side effects, so close monitoring by your doctor is needed.
More recently, a number of new biological agents have become available for the treatment of psoriasis. These medicines, called 'immunomodulators', modify the immune system and include:
- infliximab (brand name Remicade);
- etanercept (Enbrel);
- adalimumab (Humira);
- secukinumab (Cosentyx);
- ustekinumab (Stelara); and
- ixekizumab (Taltz).
While effective, these medicines (which are all given by injection) are expensive and can also have severe side effects, so their use in Australia is currently limited to those with severe disease who have not responded to other treatments.
The following measures can help in the treatment of psoriasis:
- using soap substitutes;
- avoiding known psoriasis triggers;
- quitting smoking;
- not drinking excessive amounts of alcohol;
- maintaining a healthy weight through healthy diet and exercise; and
- managing stress.
Support for people with psoriasis
Although psoriasis usually does not affect a person’s general health (except if associated with arthritis), the disease and its treatment can interfere with daily activities and lead to depression and loss of self-esteem.
If psoriasis is affecting your well-being then it is important to discuss this with your doctor. Visible psoriasis lesions can be covered up with clothing and cosmetics if they are causing distress or making you feel self-conscious.
Many people find that educating themselves about psoriasis and joining a support group can be helpful. Support groups enable people with psoriasis to help each other by sharing advice and understanding on dealing with the disease.
2. Psoriasis (published Nov 2015). In: eTG complete. Melbourne: Therapeutic Guidelines Limited; 2017 Mar. http://online.tg.org.au/complete/ (accessed May 2017).
3. Mayo Clinic. Psoriasis (updated 17 Jun 2015). http://www.mayoclinic.org/diseases-conditions/psoriasis/basics/definition/con-20030838 (accessed May 2017).