What causes Psoriasis?

While the exact cause of psoriasis is not known, the immune system and a person’s genetics are both involved.

Normally when your skin grows, the cells move up from lower layers in the skin, up towards the top layer of skin that you see. This normally takes about 28 days, but in psoriasis the whole process is sped up and takes about four days. This means the cells are not fully formed when they reach the surface, causing a build-up of dead skin cells, which look like silvery scales. There is also an increase in blood flowing to the surface of your skin. This causes redness and the skin to thicken into raised red, scaly, plaques.


Often people who have family members with psoriasis get it too, which is why it’s thought to be a condition caused by your genes. Research has found some genes that might be linked to psoriasis, but it is not yet clear how.

Immune system

T-cells are a type of immune cell your body uses to fight disease and infections. In an autoimmune disease, which psoriasis is, your T-cells attack your body’s healthy cells because they mistake them for germs. This means the deepest layer of your skin makes new skin cells more quickly than normal. It is not known why your T-cells decide to attack your skin cells.

Triggers for psoriasis

Certain things may cause your psoriasis to get worse, these triggers will be different from person to person:

  • Stress
  • Drinking excessive amounts of alcohol
  • Smoking
  • Hormonal changes, especially in women such as puberty or menopause
  • Streptococcal throat infections, usually in children or young adults
  • Some medications e.g. lithium (depression medication), some anti-malaria tablets, ACE inhibitors (blood pressure or heart medicines)

Psoriasis is not contagious and cannot be caught from another person