Psoriasis is a common inflammatory disease of the skin which affects 2-3% of New Zealanders.
Characteristic symptoms are thick, red skin, with flaky, silver-white patches. These patches can be small and may or may not be itchy and sore. More severe cases can cover large areas of the body and have a major impact on quality of life. The aim of treatment is to minimise symptoms and prevent infection of the skin.
Psoriasis is often a life-long condition. Anyone can get psoriasis, but it is more likely to occur in people aged between 15 and 35 years and those aged between 50 and 60 years. It is not contagious, i.e. it cannot be caught from or spread to another person.
There are several different types of psoriasis, each with its own distinctive appearance. Some people will develop stiff swollen joints in combination with their psoriasis – a condition known as psoriatic arthritis. The persistent visual, and sometimes disabling, nature of psoriasis can result in social, psychological, and economic consequences for people with the condition. Hence, it is important to seek effective treatment and support.
Causes and complications
The cause of psoriasis is not fully understood but it is thought to occur when environmental factors (or triggers) interact with the body’s immune system in people who have a genetic predisposition to the condition, i.e. people who inherit a specific type of gene. This interaction results in increased production of skin cells, leading to cells rapidly building up on the surface of the skin. Environmental factors that can trigger psoriasis in susceptible people include:
- Heavy alcohol consumption
- Injury to the skin
- Bacterial or viral infections, including sore throat and strep throat
- Physical trauma
- Emotional stress
- Certain medications, including high blood pressure and antimalarial drugs.
Possible complications resulting from psoriasis include skin infections (that result from vigorous scratching), depression, stress, anxiety, heart disease, obesity, diabetes, and inflammatory bowel disease. In addition, psoriatic arthritis can lead to joint damage.
Signs and symptoms
Psoriasis may appear anywhere on the body but will often affect the elbows, knees, scalp and lower back. For some people, psoriasis appears as a few spots of dandruff-like scaling that is more of a nuisance than anything else. In other people, it is a severe condition that is painful, disfiguring, and disabling. Signs and symptoms of psoriasis vary depending on the type of psoriasis. They typically include one or more of the following:
- Red raised patches of skin covered with loose silvery scales (plaques)
- Dry cracked skin (which may bleed)
- Itching, burning, and soreness
- Thick, pitted or ridged nails
- Swollen, painful, and stiff joints
- Eye problems - conjunctivitis, uveitis or blepharitis.
Symptoms come and go in cycles of remission (disappearance) and flare-up (return) over a lifetime.
Your doctor or skin specialist (dermatologist) can usually diagnose psoriasis by taking a full medical history and examining your skin, scalp, and nails. In some cases your doctor may take a small sample of skin (biopsy) to determine the type of psoriasis and to rule out other skin conditions, such as eczema or fungal infection. X-rays may be taken if you have joint pain.
There is no cure for psoriasis but many treatments that offer significant symptom relief are available. A series, or sequence, of treatments is usually required as treatments that work well initially may lose their effectiveness over time. There are three main types of treatment for psoriasis:
1. Creams, ointments and shampoos
Most of the time psoriasis is treated by applying topical medications to reduce inflammation and itching, remove dead skin cells, and to slow the growth of skin cells. Topical treatments include:
- Corticosteroid creams and ointments
- Creams or ointments that contain coal tar
- Creams containing salicylic acid
- Anti-dandruff shampoos
- Retinoid (vitamin A derivative) or vitamin D creams.
Phototherapy, or light therapy, is a treatment involving exposing the skin to specific types of artificial ultraviolet light, which helps to slow the growth of skin cells and reduce scaling and inflammation.
Systemic (whole body) medications used for treatment of psoriasis are drugs that suppress or modify the behaviour of the immune system. They are usually used only in people with moderate to severe forms of psoriasis. Oral drugs, such as methotrexate and cyclosporine, are usually tried first. Drugs called biologicals, such as adalimumab and infliximab, which are given by injection, are used when oral drugs no longer work.
Forms of self-therapy that may help to improve the appearance and feel of affected skin include:
- Taking daily baths, adding bath oil, colloidal oatmeal, or Epsom salts
- Using moisturizer (ointment-based moisturisers are best, and should be applied immediately after bathing or showering)
- Covering affected areas overnight
- Exposing affected skin to small amounts of sunlight
- Relaxation therapy (to reduce stress)
- Eating healthy foods.
There are no specific ways to prevent psoriasis. However, keeping your skin clean and moist and avoiding known trigger factors, if possible, may help to reduce the number of flare ups. Avoiding alcohol and stopping smoking may also be beneficial. There is also evidence that weight loss can help in controlling psoriasis.
Further information and support
Psoriasis Association Southland (NZ)
Phone: (03) 216 8662
Kim, W.B., Jerome, D., Yeung, J. (2017). Diagnosis and management of psoriasis. Can Fam Physician. 2017;63(4):278–285
Habashy, J. (2017). Psoriasis (Web Page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. https://emedicine.medscape.com/article/1943419-overview [Accessed: 13/02/18]
Mayo Clinic (2017). Psoriasis (Web Page). Rochester, NY: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/psoriasis/symptoms-causes/syc-20355840 [Accessed: 13/02/18]
Reviewed: February 2018