Psoriasis is defined as a chronic skin disorder that commonly affects 1% to 3% of the world’s population.  Psoriasis is characterized by periodic flare-ups of red patched covered by a silvery and flakey scale typically on the scalp.

There are several variations of psoriasis, but the most common plaque psoriasis, but the exact cause of psoriasis is unknown.  It is believed that a combination of several factors contribute to the development of psoriasis. 

In an immune system that functions normally, white blood cells produce antibodies to bacteria and viruses.  These white blood cells also produce chemicals which help to aid in healing and fighting infective agents.  Psoriasis causes special white blood cells, called T-cells, to become overactive.

T-cells attack the skin which sets off a series of events which make the skin cells multiply quickly enough so they start to stack up on the surface of the skin.  Normal skin cells are typically sloughed off every thirty days, but in plaque psoriasis the skin goes through the entire process in three to six days. 

Psoriasis is a very complicated skin disorder which is a chronic condition.  Psoriasis is caused by one or more mutations in certain genes which trigger cells in the immune system to attack the skin.  There are several environmental factors which can trigger a psoriasis flare up.

Certain injuries to the skin can cause the formation of a psoriasis patch and may also occur in other skin diseases, including eczema.  Types of injuries that may trigger a flare include sunburns, viral rashes, drug rashes, increased friction from clothing or skin rubbing against skin in folds, or mild abrasion. 

Weather is another strong factor in triggering psoriasis.  Exposure to direct sunlight tends to help improve psoriasis, but cold and shorter days, as seen in the winter months, can trigger the rash to worsen.  Psychological stress has been a common trigger for psoriasis flares, but studies are still unclear as to why this occurs.

Hassles of everyday life can trigger a flare as well, which is understandably frustrating for those who suffer from psoriasis.  Low levels of calcium have also been reported to trigger a psoriasis flare up, but low levels of vitamin D do not trigger a flare up. 

There are several different types of psoriasis, including plaque psoriasis which is the most common type.  Plaque psoriasis usually appears as thick, flaky patches of skin on one or more parts of the body.  Sometimes the patches that affect the skin are large and may occur anywhere on the body.

Plaque psoriasis can occur anywhere on the body and the common body parts affected are elbows, knees, scalp, arms and legs.  These patches usually do not itch, but will become inflamed if scratched.  Guttate psoriasis usually affects children and young adults and appears as small red bumps.

These bumps appear suddenly, often after several weeks after an infection such as strep throat.  All treatments used for widespread, severe psoriasis have side effects when used for a long period of time.  In this case the treating physician will switch to another treatment.