About Psoriasis

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What is psoriasis?

Psoriasis (sor-i’ah-sis) is a long-term (chronic) scaling disease of the skin, which affects 1% to 3% of the UK population. IT IS NOT CONTAGIOUS. It appears as red, raised scaly patches known as plaques. Any part of the skin surface may be involved, but the plaques most commonly appear on the elbows, knees and scalp. It can be itchy, but is not usually painful. Nail changes, including pitting and ridging, are present in 40% to 50% of people with psoriasis and 10% to 20% of people with psoriasis will develop psoriatic arthritis.

Although the commonest form features red, raised, scaly plaques, there are a number of types of psoriasis. These look different and may require specific treatment.

Remember, although psoriasis is a chronic condition it can be controlled and go into remission (go away; often temporarily and sometimes permanently). Not all people will be affected in the same way and doctors will class the condition as mild, moderate or severe.

Mild psoriasis (80% of people affected) involves a few patches that may need treatment but are not likely to cause problems and can be easily controlled.

Moderate psoriasis (15% of people) affects more skin the condition is widespread but again can usually be controlled with self-management under the supervision of a GP or nurse.

Severe psoriasis (5% of people) results in large areas being covered with psoriasis; the condition becomes difficult to self-manage or no longer responds to treatment. At this stage referral to secondary care at a local hospital outpatient department or in extreme cases an inpatient stay may be felt necessary in order to provide optimum care (best or most suitable) and monitoring.

What happens?

Normally a skin cell matures in 21 to 28 days. During this time it travels to the surface of the skin, where it is lost in a constant, invisible shedding of dead cells. In patches of psoriasis the turnover of skin cells is much faster, around four to seven days, and this means that even live cells can reach the surface and accumulate with dead cells. The extent of psoriasis and how it affects an individual varies from person to person. Some may only be mildly affected with a tiny patch hidden away which does not bother them, while others may have large, visible areas of skin involved that significantly affect daily life and relationships. The process is the same wherever it occurs on the body.

Who does it affect?

It affects men, women and children alike. It can appear at any age in varying degrees but usually between the ages of 10 and 30. The severity of the disease varies enormously – from a minute patch to large patches covering most body areas. Psoriasis can also run in families and much research is being done into the genetics of this disease. It is known that the disease is multi-genetic (a condition where several genes may each have different roles, contributing to specific characteristics of disease) and therefore children may not necessarily inherit psoriasis. It is estimated that if one parent has psoriasis then there is a 15% chance that a child will develop the condition. If both parents have psoriasis this increases to about 75%. Interestingly, if a child develops psoriasis and neither parent is affected there is a 20% chance that a brother or sister will also get psoriasis. This is because the condition is known to skip generations, so somewhere there will be a familial link to a relative via either or both parents.

Is there a cure for psoriasis?

Unfortunately not at the moment. Much research is being done and in the last decade great strides have been made in understanding what goes wrong in psoriasis, so there is good cause for optimism.

In the meantime there are a number of treatments that are effective in keeping the problem under control. The art of treating psoriasis is finding the best form of treatment for each individual. There is no single solution that is right for everyone.

Does this mean I will have psoriasis for life?

In the absence of a cure you will always have psoriasis, but this does not mean that the signs will always be visible. Normally, the rash tends to wax and wane (increasing and decreasing). There will be periods when your skin is good, with little or no sign of psoriasis. Equally, there will be times when it flares up. The length of time between clear skin and flare-ups differs for each individual and is unpredictable. It may be weeks, months or even years. 

What are the types of psoriasis?

Chronic plaque psoriasis: Raised, red, scaly patches mainly occurring on the limbs and the trunk, especially on the elbows, knees, hands, around the navel, over the lower back (sacrum) and on the scalp. The nails may be affected so that they become thickened and raised from their nail beds, and the surface of the nail may be marked with small indentations (pits). This is the most common type of psoriasis, affecting approximately 9 out of 10 people with psoriasis.

Guttate psoriasis(Raindrop psoriasis) 
Guttate psoriasis

So named because it manifests itself over the body in the form of scaly, droplet-like patches. Numerous small, red, scaly patches quickly develop over a wide area of skin, although the palms and the soles are usually not affected. It occurs most frequently in children and teenagers, often after a throat infection due to streptococcal bacteria. Some people who have had guttate psoriasis will go on in later life to develop chronic plaque psoriasis.

Scalp psoriasis
Scalp psoriasis

Raised, red, thick, scaly plaques on the scalp and around the hairline. It is common and approximately 50% of all people with psoriasis have it on their scalp. The reason it deserves special mention is that it can be particularly difficult to treat and usually requires specifically formulated medicines. It is awkward to treat with creams and ointments because the hair gets in the way.  Go to scalp psoriasis article.

Flexural psoriasis
(sometimes known as inverse psoriasis)
Flexural psoriasis

Produces red, well-defined areas in skin folds (flexures) such as the armpits, between the buttocks and under the breasts .Scaling is minimal or absent. This type of psoriasis can be frequently irritated by rubbing and sweating due to its location in the skin folds and other tender areas. Such areas can also be prone to yeast or fungal infections, which might cause confusion in diagnosis. Go to sensitive areas article.

Napkin psoriasis

Napkin psoriasis: Develops in the nappy area of an infant to cause a bright red, weeping rash or more typical psoriasis plaques. A child who has napkin psoriasis as a baby does not seem to have a higher risk of developing other forms of psoriasis in later life.

Palmar plantar pustular psoriasis

Palmar plantar pustular psoriasis
Palmar plantar Pustular psoriasis: Small, deep-seated pustules form that usually only affect the palms and soles. Pustules are caused by the accumulation of white blood cells and are not infected. Go to pustular psoriasis article.

Generalised pustuar psoriasis
Generalised pustuar psoriasis

Generalised pustular psoriasis: In rarer cases, the pustules are more widespread, with fever and a high white blood cell count. The development of generalised Pustular psoriasis requires urgent hospital treatment.. Go to pustular psoriasis article.

Erythrodermic psoriasis
Erythrodermic psoriasis

Erythrodermic psoriasis: A rare, serious condition where skin redness (erythema) can affect the whole body. Dilated blood vessels in the skin affect blood circulation to other parts of the body, with problems of fluid balance and rapid heat loss. In severe cases, this may be life-threatening. Erythrodermic psoriasis is very rare, with approximately 200 to 300 new cases in the UK each year. These patients need very intensive specialist care in hospital.

Nail psoriasis
Nail psoriasis

In 40% to 50% of people with psoriasis there is also major involvement of the nails, with minor involvement seen in some individuals. The fingernails and toenails are affected equally. This may just be one nail, or all of them. Discolouration, pitting and separation from the nail bed (onycholysis) are the most common characteristics of activity. Nails can be a good indicator that psoriasis is present and can help the doctor to diagnose if an associated form of arthritis is present.  Go to nail psoriasis article.

Psoriatic arthritis (psoriatic arthropathy)
Psoriatic arthritis
Psoriatic arthritis (psoriatic arthropathy): About 10% to 20% of people with psoriasis may develop an associated arthritis called psoriatic arthropathy, which causes pain and swelling in the joints and connective tissue, accompanied by stiffness particularly in the mornings and when rising from a seat. Most commonly affected sites are the hands, feet, lower back, neck and knees, with movement in these areas becoming severely limited. Chronic fatigue is a common complaint linked with this condition. If you are experiencing mild aches and pains and have psoriasis, even very mildly, consult your dermatologist for further advice and if necessary a referral to a rheumatologist for further assessments.  Go to psoriatic arthritis article.

What can I do to help treat my psoriasis?

There may not be a cure yet but there is much you can do to help maintain and control your psoriasis. Psoriasis, regardless of location or type, is often irritated by contact, particularly tight clothing such as elasticated waistbands, socks, tights, and underwear. It may be useful to wear looser clothing where psoriasis is likely to be irritated either when flaring or during periods of treatment.

Most people who have psoriasis find that the sun helps to improve their skin’s appearance. For some the change is dramatic. See  Psoriasis and the Sun and Psoriasis and Phototherapy  for more details.

Your general practitioner or dermatologist will be best placed to advise you and keep you informed of all current and new treatments available and to recommend the best treatment programme for you personally.

Remember: Your treatment can only be as good as you allow it to be - that means if the treatment takes six weeks, you have to follow it as instructed for six weeks and no ducking out! Adherence to treatment instructions is an essential part of managing your psoriasis. See  Treatments for psoriasis 

Finding out all you can about psoriasis and having a full working understanding can be very helpful in coping with the problem. Look out for any emerging patterns, stress levels and any event that may trigger flare-ups. It is useful to keep a diary. 

Can diet affect my psoriasis?

A healthy diet is important for wellbeing and can reduce your risk of many long-term illnesses. However, there is no clear link between what you eat and the severity of psoriasis symptoms.

  • The British Nutrition Foundation suggests eating at least 300g of oily fish per week for general health (for example mackerel, herring, salmon, trout, sardines, pilchards).
  • Aim to eat more green leafy vegetables, nuts, seeds and wholegrain cereals, which also contain important essential fatty acids.
  • Cut back on saturated fats and vegetable oils and use more olive oil and rapeseed oil products.
  • Eat fresh, homemade foods rather than pre-packaged convenience food.
  • Excessive amounts of alcohol can make psoriasis worse and can also interfere with certain drug medications, for example methotrexate.

I may have psoriasis – what do I do now?

If you think you have psoriasis, go and see your GP. He or she may decide themselves to start treatment or refer you to a dermatologist for advice.

Don’t forget, if you are also experiencing aches and pains in any of your joints (psoriatic arthritis), have any other symptoms or if you have a family history of psoriasis, inform the doctor. This will assist with diagnosis and treatment. 


  • In the UK, approximately 1% to 3% of the population have some form of psoriasis; between one and two million people.
  • Psoriasis usually appears between the ages of 10 and 30, but it can occur at any time from infancy to old age.
  • 10% to 20% of people with psoriasis will go on to develop some form of psoriatic arthritis (inflamed joints).
  • 50% of people will have some involvement of the nails, but this is only severe in 5% to 10% of cases.
  • Erythrodermic psoriasis is very rare. There are approximately 200 to 300 new cases in the UK each year. It needs to be treated in a hospital setting.


Remember: All treatments may have unwanted side effects or require special precautions (for example, during pregnancy). Always make sure you have all the relevant information available before embarking on any course of therapy. This includes reading the Patient Information Leaflets (PIL) provided with your medicines.

This article is adapted from the What is Psoriasis? leaflet. 

Download full leaflet as a pdf


Full text with references

Always consult your doctor or healthcare provider.


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