Psoriasis Help Organisation - Online Psoriasis Forum

However, exposure to certain stimuli, such as a streptococcal infection in the throat, alcohol, medicines or local irritation or damage to the skin, may cause an outbreak of psoriasis in persons who have this genetic predisposition.

There are two main types of psoriasis: Psoriasis vulgaris (plaque psoriasis) and Psoriasis pustulosa (pustular psoriasis). The different types of psoriasis can be divided into subgroups according to severity, duration, location on the body and appearance of the lesions.

Around six percent of the people who have psoriasis also get psoriatic arthritis in the joints. Psoriatic arthritis primarily occurs in fingers and toes, but is also quite common in the back bone.

Psoriasis is driven by the immune system, especially involving a type of white blood cell called a T cell. Normally, T cells help protect the body against infection and disease. In the case of psoriasis, T cells are put into action by mistake and become so active that they trigger other immune responses, which lead to inflammation and to rapid turnover of skin cells. These cells pile up on the surface of the skin, forming itchy patches or plaques.

The first outbreak of psoriasis is often triggered by emotional or mental stress or physical skin injury, but heredity is a major factor as well. In about one-third of the cases, there is a family history of psoriasis. Researchers have studied a large number of families affected by psoriasis and identified genes linked to the disease. (Genes govern every bodily function and determine the inherited traits passed from parent to child.)

People with psoriasis may notice that there are times when their skin worsens, then improves. Conditions that may cause flareups include infections, stress, and changes in climate that dry the skin. Also, certain medicines, including Lithium salt and beta blockers, which are prescribed for high blood pressure, may trigger an outbreak or worsen the disease.