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What is Psoriasis?

Last updated on 3rd May 2023

In the UK, between 1.3% and 2.2% of the population are estimated to suffer from psoriasis, usually being triggered before the age of 35.

What is psoriasis?

Psoriasis is a long-term autoimmune condition that affects the skin, in which the skin becomes inflamed, scaly and itchy. The skin condition is chronic, meaning it is lifelong. It ranges in severity, from mild cases to suffering from severe symptoms.

There are different forms of psoriasis that affect different areas of the body and at different ages:

Plaque Psoriasis

This type of psoriasis is the most frequently diagnosed form. It is characterised by dry, raised skin patches, called plaques. These are itchy and scaly, usually seen on the scalp, lower back, knees and elbows.

Nail Psoriasis

This type of psoriasis affects both the fingernails and toenails, which can lead to the nail disintegrating and falling from the nailbed. Nails may grow abnormally.

Inverse Psoriasis

This type of psoriasis affects the folding areas on the body, such as between the buttocks and underneath the breasts, becoming more aggravated by the sweat accumulated there.

Guttate Psoriasis

This type of psoriasis usually affects young people and children, and is characterised by small scaly patches on the torso, arms and legs. It is thought to be brought on by a bacterial infection, and is temporary.

Erythrodermic Psoriasis

This type of psoriasis is rare, and extends throughout the entire body with a rash that exposes the under layers of the skin and peels. Itching and burning is extremely painful.

Pustular Psoriasis

Again, a rare form of the skin condition, pustular psoriasis is characterised by blisters filled with pus, typically seen on the palms of the hands and the soles of the feet.

Man suffering with psoriasis

What are the signs and symptoms of psoriasis?

Symptoms of psoriasis frequently include:

  • Dry skin.
  • Cracked skin, sometimes with bleeding.
  • Scaly patches of skin, usually on the knees, elbows and scalp, but can form anywhere.
  • Rashes that present differently on different tones of skin. On white skin, rashes are pink or red with a silver scale. On darker skin tones, rashes can be more of a purple colour, with grey scaling.
  • Flare-ups of the symptoms, and periods with few to no symptoms.
  • Weakened, discoloured and brittle nails.

Sometimes, people with psoriasis also have psoriatic arthritis, a condition that causes painful swollen joints.

There are potential complications involved with psoriasis, which include:

  • Issues with the eyes, including conjunctivitis.
  • Obesity.
  • High blood pressure.
  • Type 2 diabetes.
  • Cardiovascular disease.
  • Additional autoimmune diseases.

What causes psoriasis?

Psoriasis is an inflammatory skin condition triggered by an autoimmune response. White blood cells are responsible for helping the body to heal when it is presented with an infection. In a person with an autoimmune disease, the white blood cells confuse healthy cells for infected cells, and mistakenly attack them, in this case, the skin cells.

This causes the skin to renew too quickly, which causes the extra skin to accumulate, which is what we see in the rashes and scales. An autoimmune disease usually continues throughout a person’s life, sometimes with periods of few symptoms and other times with flare-ups.

It has been found that the risk of developing psoriasis increases when there is a family history of the condition, with a 10% chance of developing it if one of your parents has it, and a 50% chance if both of your parents have it.

Can psoriasis be prevented?

There is no cure or prevention for psoriasis, as with any other autoimmune disease, but there are methods of treating the condition to avoid flare-ups in the future.

Cold weather causing a flare up of psoriasis

What triggers psoriasis?

There are a number of factors that can trigger the onset of psoriasis, or a flare-up.

These are:


Cold, dry weather has been known to trigger psoriasis flares, due to a lack of sunlight and little humidity. During colder months, people often use indoor heating which causes the air to dry out, causing your skin to become dry as well. People are more likely to become unwell in colder months too, causing the immune system to go into overdrive. Warm weather is likely to help to calm a psoriasis flare-up due to the heat and humidity.


Stress is a well-known trigger for psoriasis. It is an unfortunate cyclical process, as stress can trigger flare-ups, which in turn causes more stress. Stress can cause itching to be heightened. Many people experience their first flare-up during a stressful time.

Excess alcohol and smoking

Studies have shown that, on average, people with psoriasis tend to consume more alcohol than people without the condition. There is a strong connection between alcohol abuse and psoriasis. Smoking increases the intensity of psoriasis flare-ups and makes the risk of other inflammatory conditions higher. There are a number of conditions that psoriasis is linked to, such as cardiovascular disease and lung cancer, which smoking worsens.


Some women find that psoriasis is triggered by changes in their hormones, around puberty, during or after pregnancy, during menopause or through birth control medications.

Other immune conditions

Other conditions that affect the immune system can cause the immune system to over-compromise and trigger a psoriasis flare-up.


Some medications can trigger flare-ups of psoriasis, such as antimalarial drugs, NSAIDs such as ibuprofen, and angiotensin-converting enzyme inhibitors that are used to reduce high blood pressure.

Streptococcal throat infection

This usually occurs in children, where guttate psoriasis develops after a streptococcal throat infection, though many people do not develop psoriasis.

Living with psoriasis

Many people find effective treatments for psoriasis; thus, it is not majorly disruptive to their day-to-day lives. However, for some people, it can deeply affect the quality of their lives. Psoriasis is a chronic, incurable condition, and this inevitably has a big impact.

In addition to the physical pain and discomfort of more severe instances of psoriasis, managing stress levels is difficult, and people with the condition need to pay particular attention to how much they take on, and their levels of stress generally. It is important for people with psoriasis, and their loved ones, to be aware of the triggers for flare-ups.

Additionally, depression is very common in people with psoriasis. It is unclear which precedes which, but depression should be taken seriously, and not seen solely as sadness with one’s outward appearance.

Whilst there is no substantial evidence to suggest that someone with psoriasis will have a shorter life expectancy than a healthy person, there are complications involved with autoimmune diseases that can lead to premature death.

How is psoriasis diagnosed?

A diagnosis for psoriasis will require an examination of your skin, your scalp and your nails. If the clinician is uncertain as to which type of psoriasis you may have, they will likely take a tiny skin sample and examine it underneath a microscope.

Woman looking at skin sample for diagnosis

How is psoriasis treated?

There is no cure for psoriasis, but there are treatments that can help to control symptoms and calm flare-ups, which can usually be prescribed by a general practitioner, rather than a specialist. You will only be referred to a specialist if the case of psoriasis is very severe, or treatments are having little to no impact.

There are different types of treatment available:


Topical treatments include creams, balms and ointments that are applied directly to the skin. There is no guarantee that the first one you use will help, and the doctor will usually start with the low-strength cream and work up from there if necessary. It is also possible to buy some topical moisturisers and emollients over the counter, without a prescription.

  • You can purchase emollients, which can be effective to help ease flare-ups, as they work by trapping moisture in the skin.
  • Salicylic acid is sometimes used to help exfoliate the dead skin cells, and comes in many different forms. Other topical treatments have a better chance of working when the layer of dead skin is removed.

Topical treatments via prescription may include:

  • Steroids. These may be effective as they help to slow down the rate at which the skin grows. These may be prescribed if you have many areas of affected skin. However, there are side effects to using steroid creams, which can affect the skin in other ways, such as thinning skin, bruising and broken blood vessels. Overuse of steroids has been linked to cancer.
  • Vitamin D. Your doctor may prescribe medications such as Calcipotriene or Calcitriol, which are manufactured ointment forms of vitamin D. In some cases, the doctor may suggest that you take a vitamin D and steroid combination.
  • Retinols. Using a retinoid, which contains vitamin A, can help to increase the rate at which the skin sheds.


In some cases, topical treatments aren’t effective enough. They may work for a while, and then cease to help ease symptoms. In this case, other routes such as phototherapy may be explored.

Phototherapy is a light therapy that has often proven to be effective in treating psoriasis. Using ultraviolet light type B (UVB), which is not able to be seen by the human eye, the skin is exposed to the light rays, which helps to slow down the rate at which the skin cells are produced. This type of phototherapy may last for up to 8 weeks.

Another type of phototherapy is one using PUVA, Psoralen plus ultraviolet. This is a slight different process, as you are exposed to ultraviolet light A (UVA), which can affect your skin more deeply than UVB. For this treatment, you will need to take a tablet which contains psoralens, which increases skin sensitivity to UVA. This treatment has side effects such as headaches and burning, and should only be considered in cases of severe psoriasis, where other treatments have not helped. It should not be considered a long-term treatment, due to the risk of developing skin cancer.

Light therapy and topical treatment can be done simultaneously, depending on the medication.


If you have tried other methods of treatment and they are ineffective, you may be offered a treatment that works through the body, rather than targeted treatments. These are usually very effective, but can have dangerous side effects and risks involved.

Biological treatments are administered in injection form. These include Etanercerpt, Adalimumbab, Infliximab and Ustekinumab. They all carry a risk of severe, potentially life-threatening infection.

  • Etanercerpt is administered twice weekly, though there is a chance that you could come down with an infection. People who have a history of Tuberculosis should avoid this drug, as it may occur again.
  • Adalimumbab is administered twice weekly. Nausea and a rash where the injection was given are common. Again, there is a risk of an extreme infection.
  • Infliximab is administered via a drip, and must be done in a medical care setting. With a risk of severe infection, it should be approached cautiously.
  • Ustekinumab is injected every 12 weeks, and can trigger a throat infection and rash.

Non-biological oral medications are taken in tablet form, and include Methotrexate, Ciclosporin, Acitretin, Apremilast and Dimethyl Fumarate.

  • Methotrexate reduces the production rate of skin cells. It can be harmful to anyone with liver conditions, and can also affect the production of blood cells. Any woman who takes methotrexate should avoid becoming pregnant when taking the medication, and for six months afterwards. Men should also avoid conceiving a child in that same time frame.
  • Ciclosporin is an immunosuppressive drug, though it can increase blood pressure and the risk of kidney disease.
  • Acitretin is a retinoid that is ingested orally, which slows down skin cell production. However, it can lead to dry cracked lips and hepatitis. Women should avoid becoming pregnant whilst taking this drug and should not conceive for three years afterwards.
  • Apremilast and dimethyl fumarate are last resort options when other methods have not worked.

Who can offer support with psoriasis?

  • The Psoriasis Association is a charity that supports people affected by psoriasis in the UK. They offer advice on treatments and forums where you can connect with people in the community.
  • The British Skin Foundation helps people with many skin conditions, including psoriasis. They conduct research into the latest treatments and potential medications.
  • Versus Arthritis offers a free helpline for people suffering from arthritis, including psoriatic arthritis.
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About the author

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Rose Winter

Rose is a qualified teacher with six years of experience teaching in secondary schools and sixth forms across London. Before this, she worked as a communications officer in the Cabinet Office. Outside of work, Rose can be found researching topics of interest and spending time abroad.

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