Psoriasis is a recurrent skin condition that affects around 2% of the population in the UK. In simple terms, it is only an acceleration of the usual replacement processes of the skin. Normally a skin cell matures in 21 to 28 days during its passage to the surface where a constant invisible shedding of dead cells, as scales, takes place. Psoriatic cells, however, are believed to turn over in two to three days and in such profusion that even live cells reach the surface and accumulate with the dead cells in visible layers. Psoriasis affects both sexes equally. It may appear for the first time at any age, although it is more likely to appear between the ages of 11 and 45.