Inflammation of the skin, either due to an inherent skin defect, direct contact with an irritating substance, or to an allergic reaction. Symptoms of dermatitis include redness, itching, and in some cases blistering.

Biologic treatment
Generally prescribed for people whose psoriasis is moderate to severe. They target very specific components of the immune system and are given as an injection under the skin (subcutaneous) or infusion (into a vein).

Cardiovascular disease
Refers to all diseases and conditions involving the heart and blood vessels.

Crohn’s disease
An inflammatory bowel disease that causes inflammation or ulceration of the digestive tract.

Proteins used by the immune system to communicate messages between cells; in psoriasis, cytokines carry messages that promote inflammation and the overly rapid development of skin cells.

Dermatology Life Quality Index (DLQI)
A scale used by doctors to assess the impact of a skin condition on quality of life.

A group of chronic skin conditions that affect the hands, scalp, face, back of the neck, and skin creases of the elbows and knees. It can run in families; however, it may occur for no known reason or be caused by an allergic reaction.

Reaction by tissue, e.g., skin, in response to infection or injury.

Inflammatory bowel disease
A disease that causes inflammation or ulceration of the digestive tract.

An injection given into a vein.

Immune system
Complex group of cells and organs that defend the body against infection and disease.

Small molecules that are produced by white blood cells and play an important role in immunity. Some interleukins encourage inflammation, while others calm it down. Three interleukins, interleukin 12 (IL-12), IL-23 and IL-17A promote inflammation and have been shown to play a critical role in the psoriatic disease process.

Patch of skin affected by psoriasis.

Metabolic syndrome
A collection of disorders – including high blood pressure, obesity, high cholesterol and insulin resistance – that together increase the risk of stroke, heart disease and type 2 diabetes.

PASI (Psoriasis Area and Severity Index)
A scale used by doctors to assess the extent and severity of psoriasis, before and after treatment.

Phototherapy (or light therapy)
Uses the same ultraviolet rays given off by the sun – UVA and UVB – to treat psoriasis.

A scaly patch formed on the skin by psoriasis; can also be referred to as a lesion.

Psoriasis is a chronic, non-contagious disease of the immune system that prompts skin cells to regenerate too quickly, causing red, scaly lesions that crack and bleed. It often affects the elbows, knees, scalp and torso but can appear anywhere on the body.

Psoriatic arthritis
Psoriatic arthritis is an inflammatory disease which causes pain, stiffness and swelling in and around the joints. Up to 35% of people with psoriasis also develop psoriatic arthritis.

The period during which the symptoms of a disease decrease or subside.

Subcutaneous injection
An injection given under the skin.

Systemic treatments
These work to address psoriasis from the inside, by targeting the immune system. They are generally only prescribed for people whose psoriasis is moderate to severe.

Topical treatments
Applied directly to the skin to help slow down excessive skin cell production and/or reduce the inflammation that psoriasis causes. They address psoriasis from the outside.

Tumour necrosis factor (TNF)
A protein in the body involved in inflammatory processes. When overproduced in the body, it also damages tissue in and around the joints of people with psoriasis.