Causes of psoriasis

Although the exact cause of psoriasis is unknown, current theories suggest that your own immune system may be involved, where it attacks the cells of your body.

The outer layer of our skin is constantly making new cells and shedding old ones. In psoriasis, the immune system becomes overactive. This over-activity results in a sped-up growth of skin cells. The normal rate at which skin cells mature and shed from the skin's surface is about 28 to 30 days.

In psoriasis, the skin cells mature much more quickly, in 3 to 6 days, and move to the skin surface. Since the skin cells grow more quickly than they can be shed, they build up on the outer layer of skin, forming scales. Why the immune system begins to respond in this way remains unclear.

Psoriasis is believed to have a genetic component, so having close relatives with psoriasis increases your risk. Certain triggers, such as stress and infections, and even some medications can make symptoms worse.