What causes Psoriasis?

It is known that the skin in Psoriasis patches is growing much quicker than normal skin. In all of us, the epidermis (the outer layer of skin) grows continuously from its under surface, and a new layer is reformed each month.

In Psoriasis, the skin reforms a complete layer of epidermis each 3-4 days - so that extra skin must be shed in scales. This procedure is similar to healing of the epidermis after an injury - except that normal skin "knows when to slow down and Psoriasis skin does not".

However the actual chemical cause of Psoriasis is not known. There have been many scientific experiments performed looking for the cause, but so far the changes found seem to result from the rapid growth, and not to cause it.

Sometimes (but certainly not always) Psoriasis can run in families, and so it is likely that there are inherited properties causing a 'tendency' to the condition. If a person has this tendency, an accident or nervous shock, or some germ infections, can set off the condition and make it appear on the skin.