Superdrug Health

Skin

Psoriasis is a common skin condition appearing as thickened red patches covered by dry, silvery white scales. The patches, or plaques as they are also known, generally appear on the knees, elbows and scalp but can occur anywhere on the body. Sometimes, in its mild form, only one or two patches will appear, but in its severe form, large numbers of patches will develop. The condition is not infectious nor is it contagious, so it cannot be passed from one person to another.

It is estimated that about 2% of the population can be affected by psoriasis. It can develop at any age, but is more likely to appear for the first time after the mid-teens. Men and women are affected equally.

Psoriasis can appear in a number of forms. The most common form is plaque psoriasis, occurring in about 8 out of 10 people who have the condition. Other forms of psoriasis include guttate psoriasis, erythrodermic psoriasis, pustular psoriasis and inverse psoriasis.

About 10-30% of people with psoriasis also develop psoriatic arthritis which affects the joints.

The thickened red patches and the silvery white scales are produced by an abnormally fast turnover of the cells of the skin. Normally, the cells in the outer layer of the skin (called the epidermis) are replaced by new cells every 3 to 4 weeks. As the old cells die, they are shed off. In psoriasis, the turnover of cells occurs at a much faster rate, occurring in as little as every 3 to 4 days. The old cells are replaced at such a fast rate that the time is too short for them to be shed fully. They remain in the area, producing the silvery white scales that are typical of psoriasis.

The causes of such an increase in skin production are unknown, however family history plays an important part as there is a genetic tendency to suffer from psoriasis. Psoriasis can also be triggered by a number of factors such as a skin injury, a throat infection, certain drugs such as antimalarials and by both physical and emotional stress.

The appearance of the thickened red psoriasis patches differs for each of the different forms of the condition.

In plaque psoriasis, the raised red patches with silvery scales tend to appear as well defined, symmetrical patches usually on the elbows, knees, scalp and trunk. The plaques may cause intense itching and burning. In about half of those with plaque psoriasis small pin holes or pits may occur on the surface of the nails, or the nails may become discoloured or become loose.

In guttate psoriasis, the patches are much smaller, about the size of a 1p coin, but are far more numerous than plaque psoriasis and occur over many areas of the body. Guttate psoriasis is most often seen in children, typically following a streptococcal (bacterial) throat infection. The patches usually disappear after a few weeks, but in some children they remain, later developing into plaque psoriasis.

In erythrodermic psoriasis, the plaques lose their well defined edge and large areas of the body become red, inflamed and scaly.

In pustular psoriasis tiny blisters filled with yellow pus appear then gradually fade to leave a small brown stain. Pustular psoriasis may affect the soles of the feet and palms of the hands, in which case it is known as plantar or palmar pustular psoriasis. A more widespread form of pustular psoriasis, known as generalised pustular psoriasis, appears as yellow pustules over large areas of the body making the sufferer feel generally unwell and feverish.

Inverse psoriasis appears as large smooth red patches where the skin folds, for example under the breasts, between the buttocks, under the armpits and in the groin. The patches are affected by friction and sweat, making them red and itch intensively.

In psoriatic arthritis, the joints are affected, particularly of the toes and fingers, making movement painful and difficult.

Medicines

At present there is no cure for psoriasis. Treatments work by controlling the patches of psoriasis so the skin appears less inflamed and less scaly.

Treatment will depend on the form of psoriasis, the severity of the condition and the area of the body affected.

Mild psoriasis
Topical treatments in the form of creams, ointments, lotions and bath additives that are applied directly to the psoriasis patches or added to bath water are normally the first approach to the treatment of mild psoriasis. Sometimes two or more topical treatments will be used together or will be used alternately.

The types of topical treatments used include:

Emollients and keratolytics - Emollients such as aqueous cream, coconut oil or white soft paraffin moisturise the skin helping to keep it soft and supple. They prevent the skin from splitting and ease irritation. Some are used instead of soap when bathing or applied before other topical treatments to help them penetrate the skin. Keratolytics include substances such as salicylic acid which are used to remove thick scales. If the psoriasis is very mild it may be possible to manage it with emollients alone.

Dithranol - slows the excessive rate at which the cells of the skin multiply. It is a very effective treatment for psoriasis but it needs to be applied carefully, directly to the psoriasis plaques, as it can cause severe irritation if it comes into contact with normal skin. A method called ‘short contact therapy’, where the dithranol containing preparation is applied for 10-60 minutes before being washed off, helps reduce skin irritation. Dithranol preparations can take up to 6 weeks to work. Dithranol stains, so care must be taken to avoid contact with clothing and bed linen, and it must be washed off any items in which it comes into contact such as bathroom fittings.

Topical steroids - these include hydrocortisone, betamethasone. They reduce the turnover rate of the epidermal cells. Topical steroids should not be used for prolonged periods and they should not be used to treat large areas because they may cause side effects and thin the skin. They are best used to treat small patches of psoriasis occurring in awkward areas such as on the scalp, on the face or in skin folds.

Tar preparations - Coal tar extract containing preparations help reduce inflammation and remove loose scales. The original tar products were very smelly and messy but have generally been replaced by refined tar preparations that are more cosmetically acceptable, but they can still stain clothing and fabrics.

Vitamin D derivatives - these include calcipotriol, calcitriol and tacalcitol. Vitamin D derivatives act by promoting normal cell growth and development. They also help to reduce inflammation. They are effective treatments, improvement occurring gradually over a period of up to 12 weeks. They do not smell or stain and are generally safe if used correctly.

Vitamin A derivatives - include tazarotene. Vitamin A derivatives, also known as retinoids, are similar to the vitamin D derivatives. Tazarotene helps normal skin development and reduces scaling. Tazarotene gel can cause irritation so it should not be applied to the face or skin folds and care should be taken to avoid contact with healthy skin.

Moderate to severe psoriasis
If your psoriasis has not responded to topical treatments or if it is too extensive for you to treat yourself, you may be referred to a dermatology clinic to be treated by a dermatologist (skin specialist). Initially, the dermatologist may try using the same topical treatments but at higher doses and for longer periods of time.

If the psoriasis does not respond then therapy using ultraviolet light will be used in a procedure known as phototherapy.

If the psoriasis still does not respond, then systemic treatments such as acitretin, ciclosporin or methotrexate taken orally in the form of capsules, tablets and liquids, or injectable treatments such as etanercept, efalizumab and infliximab that are given by injection into a vein or under the skin may be tried. These products work either by reducing the rate of cell turnover or by reducing inflammation. Most of these have severe side effects and their use needs to be closely monitored. Some are dangerous if taken by pregnant women, so if you are pregnant or want to become pregnant you must discuss this form of treatment with your doctor.

If you have a skin problem and you think that it may be psoriasis, talk to your pharmacist. Your pharmacist will be able to confirm if it is psoriasis or some other skin complaint, and whether you should go to see your doctor.

If your psoriasis is mild, you may want to try treating it yourself. Many of the topical treatments described are available without a prescription. Your pharmacist will select a product and a formulation that best suits you and the area to be treated.

If you have been prescribed any of the systemic or injectable treatments for psoriasis, let your pharmacist know, especially when buying other medicines or health food supplements as they may react dangerously together.

Consult your doctor if you are worried about psoriasis, or if you have not managed to treat the condition successfully yourself. The doctor will examine you to confirm that you have psoriasis, its particular form and the areas of the body affected. In most cases, treatments prescribed by your doctor will keep the psoriasis under control. If your psoriasis does not respond to treatment, your doctor will probably decide to refer you to a dermatologist for more intensive therapy. If your doctor thinks that you have psoriatic arthritis, you may be referred to a rheumatologist.