PSORIASIS is a common skin condition that causes skin cells to grow too quickly and build up, leaving thick, red, silvery, or scaly patches (plaques) on the surface of the skin. Psoriasis is not contagious so you cant get it from touching someone who has it. Its an accepted fact, but not proven, that men are more prone to suffering from psoriasis than women.

Symptoms

Skin patches with raised edges that are red with silvery-white scales (called plaques), rashes on genitals, scalp, or in skin folds (such as the folds you have on your knees and elbows), itching, pain, dry, cracked skin that may bleed, thickened, pitted, or discoloured nails, swollen, painful joints (psoriatic arthritis).

For most people, psoriasis patches vary in size. They can range from small spots with dandruff-like flakes to wide patches that cover large areas of skin. Mild psoriasis can be annoying, but severe cases can be disfiguring, painful, and sometimes disabling. Flares (when psoriasis gets worse) occur in cycles, with symptoms that last for weeks to months and may then lessen for some time before coming back.

Causes

Medical researchers believe that psoriasis is a chronic autoimmune skin disease; however, it has also been linked to genetic and environmental factors.

There are certain things that can trigger a psoriasis flare-up (when the psoriasis becomes worse). Such as: Certain infections (such as strep throat), certain medicines (for high blood pressure), stress, smoking, cold, dry weather, alcohol and injury to skin (insect bites/cuts/burns, etc.)

There isnt a cure for psoriasis, but there are many good ways to keep the symptoms under control with the most important being general cleanliness of the skin.

More here:

Psoriasis symptoms and causes - RTN Newspaper