Psoriasis Australia

Psoriasis Causes

The cause of psoriasis is not yet fulled understood

Researchers are yet to determine the exact cause of psoriasis. What is known is that the immune system and genetics play a key role.


Research has found that approximately 40% of people with psoriasis has a family history of the disease. Several genes have been identified that make people more susceptible to psoriasis, but there is no genetic test that can definitely tell whether an individual will develop the disease.

Immune system

The immune system has been found to play an important role in the skin changes that occur with psoriasis. 

Skin affected by psoriasis, sees immune cells enter the skin through blood vessels and cause the epidermis to grow very rapidly, (instead of the usual 21-28 days for skin not affected by psoriasis) and stop shedding properly. This causes thickening of the skin as well as the scaly build-up composed of dead skin cells that is seen on areas affected by psoriasis. Dilated blood vessels in the dermis that feed the rapidly growing epidermis cause the red color of the skin. 

Environment and behaviour

Several environmental and behavioural factors have been linked to psoriasis. These are often referred to as “triggers” and include:

  • Bacterial and viral infections
  • Certain medications
  • Physical trauma
  • Injury to the skin
  • Emotional stress
  • Smoking
  • Alcohol consumption