Psoriasis: what you need to know

What is psoriasis?

Psoriasis is a common skin condition, characterised by red, scaly patches that may be sore or itchy. The patches occur most commonly on the knees, elbows 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. There may be times when symptoms improve or disappear (remission) and other times when symptoms worsen.

Although people of any age can be affected, the most common age for psoriasis to start is late teens to early adulthood. There is a second peak in the 50s.

What causes psoriasis?

The exact cause of psoriasis is not known. However, it is known that the immune system in the skin is overactive in people with psoriasis. A type of immune cell known as a T cell builds up in the skin. These T cells and the chemicals they produce trigger the skin cells to turn over at a faster rate than normal – in days rather than weeks - leading to thickening of the skin and shedding as scales.

The condition tends to run in families, so inherited factors have a part to play. Also, certain factors may trigger episodes of psoriasis. These include:

  • infections (e.g. streptococcal throat infections and thrush);
  • injuries, including severe sunburn;
  • certain medicines (e.g. lithium, which is prescribed for bipolar disorder, blood pressure medicines such as beta-blockers, and antimalarial medicines);
  • stress;
  • heavy alcohol intake; and
  • smoking.

Psoriasis symptoms

The symptoms of psoriasis vary between people and also at different times. They may include:

  • red patches of skin covered with white scales;
  • skin soreness or itch;
  • dry, cracked skin;
  • nail ridges, pitting and discolouration; and
  • painful, swollen and stiff joints (in a small proportion of people).

Psoriasis treatments

Although there is no cure for psoriasis, in most cases the disease can be well controlled.

Various treatments are available for psoriasis, depending on the 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.

Some people with very mild disease may need only topical treatments (treatments applied directly to the skin). These include emollients (moisturisers), special shampoos, bath oils, and 'keratolytics' that soften and remove scale, such as salicylic acid.

Topical treatments that doctors may prescribe include ointments and creams containing corticosteroids, tar, dithranol, calcipotriol (a vitamin D-based medicine) or tazarotene (a vitamin A-based medicine).

For people whose disease isn’t controlled by topical therapies or who have quite widespread disease, another treatment option is ultraviolet light therapy (phototherapy). This requires specialist supervision, so it is mainly available through hospitals or some dermatologists’ practices.

Other treatment options for those people with more severe disease include oral medicines such as methotrexate (taken once per week), acitretin (Neotigason, a vitamin A-based medicine) and cyclosporin (Cicloral, Neoral, Sandimmun). While generally very effective, these medicines can have potentially serious side effects, so close monitoring by the doctor is required.

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 (Remicade), etanercept (Enbrel) and ustekinumab (Stelara). 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.

Other treatments

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. Many people find that educating themselves about psoriasis and finding a support group can be helpful.

Last Reviewed: 9 March 2011
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References

1. Australasian College of Dermatologists. A to Z of skin: psoriasis. http://www.dermcoll.asn.au/public/a-z_of_skin-psoriasis.asp (accessed Mar 2011).
2. Psoriasis (revised Feb 2009). In: eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited; 2010 Nov. http://online.tg.org.au/complete/ (accessed Mar 2011).
3. MayoClinic.com. Psoriasis (updated 25 Feb 2011). http://www.mayoclinic.com/health/psoriasis/DS00193 (accessed Mar 2011).
4. Naldi L, Rzany B. Psoriasis (chronic plaque). Clinical Evidence (online 9 Jan 2009). http://clinicalevidence.bmj.com/ceweb/conditions/skd/1706/1706_keypoints.jsp (accessed Mar 2011).
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