What Is Plaque Psoriasis?

  • Sofiya Star, BS.c - BS, Madical Science, The University of Edinburgh
  • Katheryn Sue Yin Xuan, MSc in Medical Biotechnology and Business Management, University of Warwick

If you have noticed sore and itchy patches of dry, red skin in areas like your elbow, knuckles or scalp, you may be suffering from a condition called plaque psoriasis. Plaque Psoriasis is a skin condition that presents with characteristic patches of raised red and dry skin. Psoriasis can be a difficult condition to live with, depending on its severity. However, there are many ways to manage the disease. 


Psoriasis affects over 125 million people worldwide.1 Approximately 85% of affected individuals have plaque psoriasis, making it the most common form of the disease.2 The National Psoriasis Foundation identifies 5 main types of psoriasis:

  • Plaque Psoriasis (Psoriatic Vulgaris): typically appears as discrete oval-shaped areas of dry skin that can appear red or purple (depending on skin tone) with overlying white scales
  • Guttate Psoriasis: this type of psoriasis is preceded by an infection and typically presents all over the back and torso as small, droplet-like red patches
  • Inverse psoriasis: This is where psoriasis plaques are found in the folds of your skin,  such as in the creases of your elbows and in the area under your arm
  • Pustular Psoriasis: This is where psoriasis plaques become filled with pus, becoming pustules as a result of chronic inflammation. Those with plaque psoriasis can eventually develop pustular psoriasis.
  • Erythrodermic Psoriasis: This is a rare form of psoriasis where a generalised rash occurs all over the body. It can potentially be life-threatening as the disease interferes with your body’s ability to regulate its own body temperature.

Causes of plaque psoriasis

The causes of psoriasis are not particularly well understood. However, what we do know is that it is an autoimmune condition. These are a group of conditions that occur when the immune system mounts an attack against the body’s own cells, in this case, skin cells. The immune system attacks these cells, causing the skin cells to multiply rapidly. This proliferation of skin cells is what causes plaques to form on the skin.3 Your genetic makeup plays an important role in making you more susceptible to developing psoriasis. It is an inherited condition. Identical twin studies showed that if one twin developed psoriasis, the other twin had a 70% chance of also developing the condition.4 Furthermore, specific genes have been identified that significantly increase the risk of developing psoriasis, such as the PSORS1 gene. It is thought to be present in roughly half of the individuals who develop psoriasis.3

Yet, plaque psoriasis can also be triggered by environmental causes. The Koebner phenomenon is associated with a few different skin conditions, plaque psoriasis being one of them. This is when a skin condition develops as a result of trauma. Additionally, certain drugs have been known to trigger the development of psoriasis, including beta blockers, lithium, immunotherapy drugs and antimalarials.5 The reaction to the drugs can initiate plaque psoriasis in a healthy person, re-activate the condition in someone who was in remission or worsen the condition in those with the disease. Bacterial infections, such as strep throat, can also trigger psoriasis, specifically guttae psoriasis. Obesity and cardiovascular disease have also been shown to worsen psoriasis.6

Signs and symptoms of plaque psoriasis

Plaque psoriasis typically causes areas of skin to become raised, dry and scaly, with a red or purple hue. It most commonly affects the skin of extensor limbs, such as the back of the elbow or the front of your knees. This is different from inverse psoriasis, which affects the flexural surfaces, such as the front of your elbow and the back of your knees. Plaque psoriasis most commonly affects the scalp (known as scalp psoriasis) and torso, but it can affect the entirety of your body. Psoriasis plaques can be itchy and can lead to cracks in the skin that bleed. In scalp psoriasis, plaques can appear at the hairline or can be hidden by the hair. Psoriasis can have effects on a person’s self-esteem and mental health as it can be a source of embarrassment when the psoriasis plaques flake away, resembling dandruff if the plaques appear on the scalp. Plaque psoriasis can also cause nail changes and small pits to appear on the nail.

People affected by plaque psoriasis can often develop a condition known as psoriatic arthritis. This is where the inflammation from the skin begins to spread to the joints. This leads to joint pain, joint immobility and swelling in the area. The National Psoriasis Foundation states that roughly 1 in 3 people with psoriasis will develop psoriatic arthritis. However, there is no link that increased psoriasis severity correlates with the development of psoriatic arthritis.

Management and treatment for plaque psoriasis

Despite the debilitating effects of the disease, plaque psoriasis can be treated. However, depending on the patient, this skin condition can be difficult to control. The first step to treating plaque psoriasis involves seeing a doctor; the doctor will take a history of your symptoms, previous health conditions and family history, as well as note which medications you currently take. They will then perform a clinical examination of your psoriasis plaques to assess the severity of the condition and confirm whether it is psoriasis or another skin condition, in turn referring you to a dermatologist. Furthermore, you may be given a leaflet and general advice about how to manage the condition, which includes increasing physical activity, losing weight and stopping smoking habits. The treatment plan for plaque psoriasis consists of:

  • First-line treatments of plaque psoriasis are topical agents. These are things like creams, gels, ointments, emollients and shampoos that you apply locally to the affected site. These topical therapies typically contain vitamin D, corticosteroids or both. These are prescribed for 4 weeks before the response is reviewed. If you do not experience relief or you have severe psoriasis, you’ll be under specialist care where phototherapy, systemic medications, or biologic medication may be given.
  • Phototherapy/light therapy is a treatment of plaque psoriasis that directs a very narrow band of ultraviolet rays onto the plaques using special light lamps. Systemic therapy refers to drugs that have a generalised anti-inflammatory effect and an immunosuppressant function in the body. Examples include methotrexate and cyclosporine. 
  • Biologics, such as infliximab, may also be used to manage the disease. This drug type essentially inhibits specific inflammatory molecules, like cytokines, by directly binding to them.

Systemic Therapies and biologics require constant monitoring as they can cause very significant side effects, making you more susceptible to serious infections due to their immunosuppressant function.  


How is plaque psoriasis diagnosed?

Plaque psoriasis is diagnosed using a patient’s history and clinical examination. The plaques have a very characteristic appearance, which will be recognisable to a healthcare provider. They’ll also be able to assess the severity of the disease by evaluating the extent of skin affliction and the impact this condition has on your mental well-being. 

How can I prevent plaque psoriasis?

In some ways, psoriasis is not preventable, which can be mainly attributed to the fact it is mostly an inherited condition. However, there are steps you can take to prevent flare-ups of chronic plaque psoriasis. These include avoiding irritants, like certain soaps and cosmetic products. If you have to take other medications, you can notify your doctor and ask if it can trigger psoriasis flare-ups.  Moisturising your skin, quickly resolving trauma to the skin, and avoiding itching in affected areas can also help keep plaque psoriasis in remission.

Is plaque psoriasis contagious? 

No, plaque psoriasis is not contagious, as are all other forms of psoriasis.   

Who is at risk of plaque psoriasis?

People who are most at risk of developing plaque psoriasis are those who have relatives with the condition. Yet, as mentioned previously, smoking, cardiovascular disease and certain drugs can also trigger psoriasis. 

How common is plaque psoriasis?

Over 125 million people worldwide have plaque psoriasis, making it a common skin condition. 

When should I see a doctor?

You should see a doctor if you notice the typical signs of plaque psoriasis, such as red/purple plaques of dry skin with overlying scales and nail pitting. Receiving a diagnosis early can help manage the disease more effectively. It is especially important to seek out a doctor if you notice that the plaques are widespread or the condition is having a significant impact on your mental well-being.


Chronic plaque psoriasis is a common skin condition, resulting in plaques of scaly, dry skin that can be associated with a range of symptoms, such as itching and flaking. It can have a significant impact on your mental wellbeing. If you suspect you have plaque psoriasis, you should see your general practitioner so you can be assessed and commence treatment.


  1. Bu J, Ding R, Zhou L, Chen X, Shen E. Epidemiology of psoriasis and comorbid diseases: A narrative review. Frontiers in Immunology. 2022;13. doi:10.3389/fimmu.2022.880201  
  2. Nair PA, Badri T. Psoriasis. [Updated 2023 Apr 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448194/
  3. Rendon A, Schäkel K. Psoriasis pathogenesis and treatment. International Journal of Molecular Sciences. 2019;20(6):1475. doi:10.3390/ijms20061475 
  4. Lønnberg AS, Skov L, Skytthe A, Kyvik KO, Pedersen OB, Thomsen SF. Heritability of psoriasis in a large twin sample. British Journal of Dermatology. 2013;169(2):412–6. doi:10.1111/bjd.12375 
  5. Balak D, Hajdarbegovic E. Drug-induced psoriasis: Clinical perspectives. Psoriasis: Targets and Therapy. 2017;Volume 7:87–94. doi:10.2147/ptt.s126727 
  6. Kamiya K, Kishimoto M, Sugai J, Komine M, Ohtsuki M. Risk factors for the development of psoriasis. International Journal of Molecular Sciences. 2019;20(18):4347. doi:10.3390/ijms20184347 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Jeandy Mibanzo-Ilamu

Master of Research Biology of Cancer - MRes University of Liverpool

Jeandy is a final year medical student which has allowed him to acquire strong clinical knowledge and familiarity with general health and wellbeing.His master's degree focused on the Biology of Cancer, a keen area of interest and allowed him to develop a lot of the skills he uses in writing his articles.

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