Unpredictable and irritating, psoriasis is one of the most baffling and persistent of skin disorders. It's characterized by skin cells that multiply up to 10 times faster than normal. As underlying cells reach the skin's surface and die, their sheer volume causes raised, red plaques covered with white scales. psoriasis typically occurs on the knees, elbows, and scalp, and it can also affect the torso, palms, and soles of the feet.

The symptoms of psoriasis vary depending on the type you have. Some common symptoms for plaque psoriasis -- the most common variety of the condition -- include: 

• Plaques of red skin, often covered with loose, silver-colored scales; these lesions may be itchy and painful, and they sometimes crack and bleed. In severe cases, the plaques of irritated skin will grow and merge into one another, covering large areas.

• Disorders of the fingernails and toenails, including discoloration and pitting of the nails; the nails may also begin to crumble or detach from the nail bed.

• Plaques of scales or crust on the scalp

psoriasiscan also be associated with psoriasis arthritis, which leads to pain and swelling in the joints. The National psoriasis Foundation estimates that between 10% to 30% of people with psoriasis also have psoriasis arthritis.