Psoriasis (sore-eye-a-sis) is a relatively common skin condition where normal skin grows too fast. While there is no one cause, it is thought an abnormal immune response affects skin cells, causing them to speed up their normal growth and pile up instead of falling away on their own.

Common symptoms

 Psoriasis symptoms will vary from person to person and by type of psoriasis. Some of the common symptoms include:

  • Raised, red, inflamed lesions
  • Silvery scaly plaques
  • Small, red, individual spots (more common in children and young adults)
  • Dry skin that may crack and bleed
  • Itching, burning, or soreness of the skin
  • Pitted nails or separation from the nail bed

Types of psoriasis

There are 5 major types of psoriasis:
What: The most common type of psoriasis with raised, inflamed, red lesions covered by silvery white scale.
Where: Usually the elbows, knees, scalp and lower back.
Inverse (Flexural)
What: Bright red lesions that are smooth and shiny.
Where: Armpits, groin, under breasts, other skin folds around the genitals and buttocks.
What: May appear quickly, widespread skin surface is red and scaly that sheds in sheets rather than flakes. The skin may feel itchy and painful.
Where: Most of the body surface.
What: Small, red, individual spots on the skin (not as thick as palque lesions) that often starts during teens or early 20s following a bacterial infection.
Where: Torso, arms and legs.
What: Begins with reddening of the skin, followed by the formation of white blisters filled with pus (non-infectious) surrounded by red skin. There may be scaling with small brown dots.
Where: Palms of the hands and soles of the feet or occasionally on the body.

When psoriasis affects more than just the skin

Some people with psoriasis develop psoriatic arthritis (around 30 in 100 people), a condition that can also affect joints at the ends of fingers, wrists, knees and ankles. They may become stiff, painful and swollen. Like psoriasis, there are different types of psoriatic arthritis:
  • Symmetric – affects the same joints on both sides of the body, can be disabling, much like rheumatoid arthritis
  • Asymmetric – does not occur in the same joints on both sides of the body, fingers and toes may be enlarged and joints may be warm, tender and red
  • Distal interphalangeal predominant – occurs in 5 in 100 people and affects the joint closest to the nail on fingers and toes
  • Spondylitis – swelling of the spinal column, causing stiffness of the spine at the neck, lower back and hip and can also be present in the hands, arms, hips, legs and feet
  • Arthritis mutilans – occurs in fewer than 5 in 100 people and is a severe, deforming arthritis that affects small joints of the hands and feet and may cause neck or lower back pain
Since psoriasis is an immune disease, it may be associated with increased risk of hypertension, obesity, elevated lipids, heart disease, diabetes, inflammatory bowel disease, lymphoma and depression.

Cycles, flare-ups & triggers

Most types of psoriasis go through cycles. You may experience long periods (weeks or even months) of no symptoms, appearing to go into complete remission. But because psoriasis is a chronic (or long-lasting) disease, symptoms can return, or "flare up". Symptom flare-ups can be distressing, having a significant impact on your daily life. They are caused by external factors from the environment, known as triggers. Triggers affect everyone differently. Common symptom triggers include:
Stress Injury to skin#
Cold weather Smoking
Certain medications* Heavy alcohol consumption
# Cuts, scrapes, bug bites, severe sunburn
* Including lithium, anti-malarials and certain medicines to treat high blood pressure. Talk to your doctor if you're taking any of these medications.
For additional information on psoriasis, please visit www.dermnet.org.nz

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The severity of psoriasis is measured with the Psoriasis Area and Severity Index (PASI) score. It is a scale that takes into account the area of lesion coverage (calculated as the percentage of the affected body surface area) as well as plaque appearance (redness, thickness and scaling). A PASI score of:
  • ≤10 suggests mild psoriasis
  • >10 suggests moderate-to-severe psoriasis
A second assessment may also be performed that measures the impact of your psoriasis on your quality of life (called the dermatology life quality index; DLQI). Results are reported on a scale of 0 to 30:
  • 0−1 (no effect)
  • 2−5 (small effect)
  • 6−10 (moderate effect)
  • 11−20 (very large effect)
  • 21−30 (extremely large effect)


Psoriasis is usually classified as mild when you have:
  • a PASI score of <10 and Dermatology Life Quality Index (DLQI) <10
As the PASI score takes into account both the appearance and the area of the plaques, mild psoriasis could involve slight redness, thickness and/or scaling that covers a large area of your body, or it may involve severe thickness, scaling and/or redness that covers a small area of your body. Patients with mild psoriasis often feel embarrassed and self-conscious following the initial diagnosis. However, you need to remember that your GP can offer you a lot of options to manage your psoriasis.


Psoriasis is usually described as moderate-to-severe when you have:
  • a PASI score of > 10 and/or DLQI >10
As the PASI score takes into account both the appearance and the area of the plaques, moderate-to-severe psoriasis could involve severe redness, thickness and/or scaling that covers the majority of your body, or it may involve moderate redness and thickness covering large areas with severe scaling in just a few places.
    • In some cases of mild psoriasis (PASI <10 and DLQI <10), certain features may change the classification to moderate-to- severe including:
- there are areas affected that are visible with clothing on - major parts of the scalp are affected - the genitals are affected - palms of the hand and/or soles of the feet are affected - at least two fingernails are separated from the nail bed or deformed - itching that leads to scratching
  • Warrants the use of light therapy or systemic treatments
  • Affects your ability to work or your personal life (e.g. you miss work or sometimes avoid social situations because your psoriasis is flaring).
Patients with moderate-to-severe psoriasis may require more than just topical treatments in some cases. If this is the case, remember this is not uncommon and there are several other treatments that may work better for you.
This information is intended as a guide to help you understand how severe your psoriasis is. Your GP or dermatologist may be able to give you a more accurate diagnosis and determine the best treatment approach for you. If you don’t already have a dermatologist, your GP will be able to refer you to one. 

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This psoriasis treatment pathway is an example of the typical progression through the types of psoriasis treatments available. It will be dependent on the patient's severity of disease, impact on quality of life and treatment preferences, along with the treating prescriber's individual approach. It is important to talk to your GP or dermatologist regarding which psoriasis treatments may be suitable for you. Adapted from Baker C et al. Australas J Dermatol 2013;54(2):148−154.

Accessing treatments

The earlier you see your GP and get a diagnosis, the earlier treatment can start. So, if you recognise any of the symptoms listed on this site, talk to your GP.
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