Psoriasis Content from the guide to life, the universe and everything


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Faculty of Medical, Clinical and Veterinary Sciences

Skin Problems

Human Skin | Dry Skin | Psoriasis | Eczema | Greasy Skin | Dandruff | Acne | Rosacea | Seborrheic Dermatitis | Skin Cancer | Non-melanoma Skin Cancer | Melanoma | Hereditary Skin Cancer | Sensible sun exposure

Psoriasis is a non-infectious auto-immune disease, caused by activation of T-cells (a type of white blood cell) within the skin. It causes the skin to reproduce much faster than usual, resulting in redness and inflammation, often with scaly, dead skin on the surface. The appearance of these patches (sometimes called plaques or lesions) varies with different types of psoriasis.

Psoriasis can occur at any time of life, but most commonly appears in the early 20s, affects both men and women equally and tends to occur more in fair skinned people. It is often, but not always, inherited. In most sufferers, there is an environmental trigger that brings on a flare up of the problem - commonly infections (such as sore throats), stress, climate change and certain medicines. In most it tends to cycle from good to bad, although the definition of good and bad varies for everyone.

It is thought to affect about two per cent of the adult population, although it is difficult to define as for many the symptoms are mild and often not diagnosed, being mistaken for eczema or even dandruff.

Different Types of Psoriasis

Guttate Psoriasis

Appears as lots of small red patches, usually no more than 1cm in diameter, normally on the torso and limbs, sometimes with scaling. Often disappears completely once the trigger (most often stress or infection) has gone.

Plaque Psoriasis

Appears as larger red patches, around 2-5cm in diameter (but can vary greatly), usually with scaling. Occurs on torso, limbs, scalp. This is the commonest type of psoriasis and is usually chronic (long-lasting).

Scalp Psoriasis

Usually plaque psoriasis, most often occurs around the hair line. Trickier to treat than elsewhere on the body because of the difficulty in being able to see the plaques.

Psoriasis in the Nails

Appears as pitting, thickening or yellowing of the fingernails or toe nails, sometimes the nail bed can become detached. Tricky to treat because of the difficulty of getting to the affected skin below the nail. Frequently appears in patients with psoriatic arthritis.

Flexural or Inverse Psoriasis

Large red patches without scaling, in skin folds. Aggravated by sweat and friction.

Pustular Psoriasis

Small pus-filled lesions, most commonly on palms of hands and soles of feet. Sometimes with fever. Very painful, thankfully one of the less common types.

Erythrodermic Psoriasis

Large red patches with scaling covering a large proportion of the body. The skin becomes hot and dry, the body is not able to regulate temperature control properly. Not common but potentially dangerous, will often result in hospitalisation.

Psoriatic Arthropathy or Psoriatic Arthritis

A related disease that affects up to ten per cent of psoriasis patients, usually those with severe psoriasis. Like other types of arthritis, it causes pain and swelling in the joints, usually in the small joints, such as fingers, toes, wrist, ankles and sometimes in the lower back. It can be difficult to diagnose in the mildest cases because it rarely flares up at the same time as the skin. As with other types of psoriasis, symptoms can come and go in cycles. It can be severely disabling, but in most cases less than other forms of arthritis.


Self Help

Two things that must be stressed:

  • Diagnosis by a doctor or dermatologist is still necessary, even if these are the preferred methods of controlling the problem.

  • Everyone's skin reacts differently - what may be of great benefit to one person can have no effect or even make the problem worse for others.

General Skin Care

A good deal of control of psoriasis can be achieved by keeping the skin in good condition. Preventing dry skin really is a key point.


Much research has been done, which has mostly been inconclusive. The Swiss Psoriasis Association has issued a list of foods they recommend avoiding, which includes red meat, grapes and grape derivatives (such as wine), hot spices, peanuts and coffee. Many herbal and Chinese medicine practitioners also advise a 'detox' diet - eliminating anything which may cause a reaction or intolerance. It is wise to consult a doctor before embarking on any kind of very restrictive diet.


Helps nearly all people to some degree, but care must be taken, not only can sunburn cause psoriasis to worsen, but there are also the risks associated with skin cancers. A couple of hours' exposure once a week won't help much - little and often is far better.

Always get professional medical advice before using sunlamps or sunbeds - in non-professional hands these can cause great damage to the skin.

Mail Order 'Cures'

There have been several scams recently with unscrupulous traders selling product labelled as herbal or containing zinc pyrithione (a dandruff treatment) as their active ingredients, when in fact they contain strong prescription-only ingredients. Obviously, these are banned as soon as they are discovered, and not all products are guilty of this, but it is worth doing some background checking into any mail order product before buying. Be very suspicious of anything that works in days - this is usually a sign that something more potent is at work.

Alternative Therapies

There is a fair amount of anecdotal evidence that alternative treatments which aid relaxation and stress relief can be beneficial. Hypnotherapy and aromatherapy are two of these.


Every year, thousands of people flock to the Dead Sea because of its reputation for healing skin problems. The Salton Sea in the US has a similar, but not quite as good, reputation - possibly because of allegations of high pollutant levels. It is not known for certain why the Dead Sea has such good results, it is thought likely to be a combination of UV levels, salts and tars in the water and possibly the relaxing effect of a sunny holiday.

Other Things that Help

  • Soaking in a tepid bath for 15 minutes helps loosen scaling and reduce itching. Some people find coal tar solutions, emollients, oils or Dead Sea salts in the bath water helpful.

  • Wearing light cotton clothing.

  • Avoid stress and worry - learn to relax.

  • Avoid cuts and scrapes - in some people psoriasis can flare up at a point where the skin is damaged1. Switching to an electric shaver can help avoid a few. Sometimes even constant contact with the skin can cause a flare up - eye glasses and bra straps are frequent offenders.

  • Avoid exposure to strong chemicals, as these can irritate the skin. Wear cotton lined rubber gloves when using cleaning products, particularly if nail psoriasis is present. Hair colourings, perm lotions and hair removing creams can irritate too - never use these when the skin is broken. Even strong anti-perspirants can cause a reaction in some.

  • Not all types of psoriasis itch, but when they do, it can be an extremely intense. It does help not to scratch. Opinion is mixed as to if this actually makes the condition worse, but it certainly makes the plaques look more unsightly, and if made to bleed, can leave the skin open to infection.

  • The condition of the skin causes stress which makes the skin condition worse - a vicious circle that's difficult to break. It helps not to worry about it too much and not to let it rule your life.

Prescription Treatments

There are three different styles of treatment:

  • Topical (applied directly to the skin).

  • Phototherapy (exposure to sunlight or substitute).

  • Systemic (drugs taken orally).

The type of treatment offered depends on the severity, which is usually classified as a percentage of skin area affected. As a rough guide, an area the size of the palm of the hand is about one per cent of the skin surface.

  • Mild - less than two per cent.

  • Moderate - two - ten per cent.

  • Severe - more than ten per cent.

Most people will never progress beyond topical treatment, as 80% of cases are deemed mild. Only the worst cases are treated systemically. Combination of two or all types of therapy is also used.

Topical Treatments

Salicylic Acid

Used to reduce the scaling in conjunction with other topical treatments.

Coal Tar

Needs patience - can take three or four months to work. Must be washed off before exposure to the sun, as it makes skin photosensitive. Best left to air dry before dressing, as it can stain both skin and clothing. Also available in shampoos2 and bath soaks. Often seen as an old fashioned treatment, it is still the most effective means of control for many.


A derivative of vitamin D3 (not the same as food supplements). Not for use on the face or other sensitive areas as it can irritate the skin. Again, needs patience - can take three or four months to work, but seems to help in many cases.

Corticosteroids (Cortisone)

Good for temporary relief, but not for long term use, as the amount needed to clear problems gradually increases. It can come back even worse when use is discontinued. Long term use, particularly of the stronger varieties can also cause skin to thin and stretch marks to occur.


Applied for anything between 15 minutes and an hour, then showered off. Can be messy, time consuming and can irritate normal skin.


A type of vitamin A derivative (again, different from that found in food supplements). Can be irritating to normal skin. A fairly new treatment, only used for about 12 weeks at a time.

A few of the items listed may be available from a pharmacy without prescription, depending on local rules.

Some Tips for Topical Treatment

As each individual's response to treatments differs, doctors will often take a trial and error approach with topical treatments, trying those with the fewest side effects - and sometimes the least expensive - first. These are normally used in cream or ointment form, but some are available in a liquid base to make application to the scalp easier and less messy.

Make sure the instructions for application are read and followed. Some treatments only require application once a day, some three times a day - some are applied sparingly, other thickly - application of too much or not enough can do more harm than good.

Topical treatments can be time consuming to apply, if the lesions are widespread. Some people find that just treating those areas that cause the most problems will cause other untreated areas to fade.


Used to treat moderate to severe cases, or those resistant to topical treatments.


Administered by a specialist, from a light source, usually three times a week over two or three months. Sometimes combined with coal tar treatment.


Again, administered by a specialist, from a light source but in conjunction with a drug called psoralen, which makes the body more sensitive to light. Works quicker than UVB, but is more prone to producing side effects like burning. Psoralen can also cause side effects in some.

New 'Laser' Treatment

Recently given FDA approval in the US is a new UVB 'laser' which can target the plaques only, thus reducing the chances of damaging normal skin. It is a hand-held device and will be more suited to those with small areas of psoriasis rather than those with widespread lesions.


Works by suppressing the immune system. Only used in the severest forms of psoriasis, for those whom other types of treatments don't work, as they can produce nasty side effects in some people. Strict medical supervision and frequent blood tests are used to monitor progress and body functions. Some of these can also be effective against Psoriatic Arthritis, again only being used when the problem becomes disabling.


Not used as a treatment, but occasionally prescribed for guttate and pustular psoriasis, if the doctor suspects that a bacterial infection may be the trigger.


Used to relieve the symptoms in milder cases of psoriatic arthritis.

Future Treatment

As yet, there is no cure for psoriasis, all the treatments available concentrate on symptomatic treatment. The most promising areas of future treatment are in genetic research, identifying what is thought to be a faulty gene at the root of the problem, perhaps with the possibility of being able to 'switch off' the fault.

Another area of research being pursued is the kind sometimes referred to as 'magic bullet' - the ability to target only those cells that are confused and switch them off. This research is still in early stages, but shows much promise for those with severe and debilitating psoriasis and psoriatic arthritis.

For further information, there is an active and informative newsgroup at

Another useful site is the National Psoriasis Foundation, but this site is US based, so not all the treatments mentioned may necessarily be available elsewhere.

1This effect is known as Koebner's phenomenon.2Long term use of coal tar shampoos can stain fair hair orange.

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