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Psoriasis is a common skin condition that causes raised patches of inflamed skin. It varies in severity from person to person and can come and go over time. You can’t catch psoriasis or pass it on to other people.

About psoriasis

Your skin is made up of several layers, the top one of which constantly sheds old cells and replaces them with new ones from underneath. This happens in a cycle that usually takes about 28 days. If you have psoriasis, the rate at which your skin is replaced in the affected area increases and the cycle can be as short as two to six days. New skin cells move to the surface before they have properly matured and build up on your skin in thick patches called plaques. There is also a build-up of a type of blood cell (called T-cells) under your skin, which causes inflammation.

Psoriasis affects about two in 100 people. It can begin at any age, but commonly develops either in early adult life between the ages of 15 and 30 or later between 50 and 60. It affects similar numbers of men and women.

Psoriasis is a life-long condition and it’s unlikely that you will ever be completely free of it. However, it tends to fluctuate in severity over time, often for no apparent reason. This means that you may have flare-ups when the symptoms are more severe, but at other times the condition may hardly be noticeable.

Psoriasis isn't contagious, so you can't catch it from other people and it doesn't spread from one part of your body to another.

Types of psoriasis

There are a number of different types of psoriasis.

Plaque psoriasis

Plaque psoriasis is the most common type of psoriasis, where you get pinkish-red, scaly plaques (raised patches), especially on your knees and elbows.

             An image showing a close-up of plaque psoriasis on the skin.

                                                              Plaque psoriasis

Flexural psoriasis

Flexural psoriasis is also known as inverse psoriasis. It affects areas where your skin folds, such as your armpits and groin area. Your skin tends to be thinner and more sensitive in these areas. Flexural psoriasis causes patches of bright red, shiny skin – these may be slightly itchy or uncomfortable. You may have flexural psoriasis at the same time as having plaques elsewhere on your body.

Pustular psoriasis

This is a rare, severe form of the condition in which small pus-filled spots (pustules) develop on your skin. If this happens all over your body, it's called generalised pustular psoriasis. This can be a life-threatening condition and you’re likely to need to be treated in hospital.

Erythrodermic psoriasis

Erythrodermic psoriasis is another rare and severe form of the condition in which your skin becomes red and inflamed all over – it looks like sunburn. The inflammation can result in serious complications and usually needs to be treated in hospital. Erythrodermic psoriasis usually only develops in people who already have another type of psoriasis.

Guttate psoriasis

In this form of psoriasis, small, scaly, inflamed spots of skin suddenly appear all over your body – their appearance is sometimes described as looking like rain droplets. It tends to affect children and young adults, often after a throat infection.

Symptoms of psoriasis

Psoriasis occurs in different forms, but you will usually have thickened, red patches of skin, which may have silver/white scales. The patches can vary in size and are clearly defined from the surrounding skin. Your skin may feel itchy, painful or sore. If you have mild symptoms, you may not be aware that you have psoriasis.

Some types of psoriasis can affect your scalp and cause redness and flaking. It can also affect your fingernails, which can become pitted, thickened or loosened from the nail bed.

If you have any of these symptoms, see your GP.

Complications of psoriasis

Some people with psoriasis develop pain or stiffness in their joints, which may be a result of a condition called psoriatic arthritis. Usually the joints in your hands and feet are affected, although you may also get it in your back, knees and hips.

Causes of psoriasis

The exact reasons why you may develop psoriasis aren’t fully understood at present. It appears that your genes are the most important factor in causing the condition because you're more likely to get psoriasis if other people in your family have it. However, this doesn’t mean you will definitely get the condition.

Environmental factors also play an important role in triggering psoriasis. These include a bacterial throat infection, the effects of certain medicines or stress. For many people, there is no obvious cause.

The genetic and environmental triggers lead to immune cells in your skin setting off inflammation. This causes your skin to start producing new cells faster than usual, leading to psoriatic plaques. What makes your immune system act like this isn't clear.

Diagnosis of psoriasis

Your GP will ask about your symptoms and examine you. He or she will probably be able to diagnose psoriasis from your symptoms and by looking at your skin and nails. Your GP may refer you to a dermatologist (a doctor who specialises in identifying and treating skin conditions) if a definite diagnosis can’t be made or if your psoriasis is:

  • extensive or severe
  • affecting your education or work
  • not responding to treatment

If you have generalised pustular psoriasis or erythrodermic psoriasis, you may need to go to hospital for urgent treatment.

Treatment of psoriasis

Although there is no cure for psoriasis, there are a number of treatments that can help relieve your symptoms. Treatments vary in how effective they are for different people and you may need to try several before you find one that works for you.


Your GP will probably advise you to use emollients – creams or lotions that moisten, soften and soothe your skin. Having a warm bath may help to soften your psoriasis – your GP may suggest adding bath oil.


Topical treatments
These are treatments that you apply to your skin. Your GP may prescribe you a medicated cream or ointment – the type and strength will depend on your psoriasis, but common treatments include the following.

  • Coal tar preparations can reduce inflammation and scaling, and are often used to treat psoriasis affecting your scalp. However, they can be smelly and messy.
  • Creams that contain dithranol can be very effective, but they are messy and can irritate healthy skin, so they aren’t often prescribed.
  • Steroid preparations are often used for localised psoriasis (for example, on your elbows or knees). You may be able to use stronger steroids on your palms and soles, or your scalp. Generally, steroid creams are only used short-term.
  • Vitamin D derivatives (such as calcipotriol or tacalcitol) can be easier to use than some of the other products, but may irritate your skin.
  • Vitamin A derivatives (retinoids) can be useful, but they are prone to causing skin irritation.

Always ask your GP for advice and read the patient information leaflet that comes with your medicine.

Oral medicines
If topical treatments don't control your symptoms, or if your psoriasis is extensive, you may be prescribed medicines that you take as tablets, such as:

  • methotrexate
  • acitretin
  • ciclosporin
  • hydroxycarbamide

These medicines work by suppressing your immune system, or by slowing down the production of skin cells. They can have severe side-effects and need to be prescribed by a doctor.

Women will be warned not to become pregnant while taking these medicines and, in some circumstances, for some time afterwards. With some of the tablets, men will also be advised that they shouldn't get their partner pregnant. This is because these medicines can cause serious damage to an unborn baby.

Biological medicines are newer treatments for psoriasis that can be very effective, but tend to be restricted to people with severe psoriasis, or if other treatments haven’t worked. They are given as an injection into your skin, or through a drip into a vein in your arm. These medicines include:

  • etanercept
  • adalimumab
  • infliximab
  • ustekinumab

Your doctor can discuss these treatments with you. You will need to have various pre-treatment tests before you can try these medicines and you will be monitored with blood tests while you're receiving the treatment.

Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Light therapy

Depending on the type and extent of your psoriasis, your doctor may recommend that you have ultraviolet (UV) light therapy.

You have the light therapy in a machine that looks similar to a shower cubicle, containing fluorescent tubes.

  • Ultraviolet B (UVB) light therapy involves shining artificial UVB light on to your skin. UVB light occurs naturally in sunlight. You will usually have the therapy two to three times a week for up to eight weeks.
  • Sometimes UVB light therapy is used in combination with topical treatments such as coal tar preparations. This combination may be effective at helping to control your symptoms by making your skin more sensitive to UVB light.
  • Psoralen and UVA light therapy (PUVA) involves combining a medicine (psoralen) that sensitises your skin to sunlight with a controlled dose of UVA light. You may have psoralen as a tablet or applied directly to your skin. You usually have the treatment twice a week for up to 10 weeks.


Produced by Polly Kerr, Bupa Health Information Team, August 2012.

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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