Psoriasis is an immune-mediated chronic skin disease, which presents as thick red skin patches with silvery scales. In psoriasis, the skin cells multiply at an accelerated rate, leading to the thickening of the skin and scaling.
This disease is caused by the immune system which mistakenly attacks the healthy skin cells. If a patient falls sick or is infected, their immune system will cause an overdrive to fight the infection. This will start another psoriasis flare-up.
Vitamin D analogues like calcipotriol and anthralin, which both regulate the cell proliferation and slows down the rate of the skin growth. By reducing the rate of cell growth, the psoriasis lesions will become less flaky and thick, reversing the skin changes in psoriasis.