Skin Allergy

Skin allergy comes in two different forms. Firstly, there is skin allergy due to contact on the skin surface with substances to which the sufferer is sensitive or allergic. A common example of this would be a lady developing an allergic rash to earrings due to her allergy to the nickel contained within earrings. A further example would be a patient suffering a rash on the face following the application of a moisturising cream because that patient is suffering from an allergy to one of the chemical constituents of that cream. This type of skin surface allergy is called "allergic contact dermatitis".

A second type of skin allergy occurs where the sufferer has some kind of internal exposure (as opposed to skin-surface exposure). Common examples of this type of problem would include eating certain foodstuffs, for example seafood, or developing a skin rash following taking medications by mouth. The different types of skin rash which can be caused by this type of problem are numerous but common ones include "urticaria", "toxic erythema" and "erythema multiforme".

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Urticaria

Urticaria is an itchy condition of the skin which often appears for no apparent reason. The affected areas of skin are usually red, sometimes they are raised above the normal skin, frequently these affected areas of skin move from one area of the body to another over a period of hours and sometimes (especially on the face) the affected areas can become very swollen for a while. Sometimes the lesions appear at sites of skin friction or scratches, even fairly minor rubbing can cause the appearance (see scratched forearm photo below). This curious type of urticaria is called dermographism. Usually the condition comes for a few days then goes away for a while although sometimes the problem is more persistent.

It is presumed that the cause of urticaria in some people is a skin reaction to 'foreign' chemicals or foreign proteins which may be introduced into the body in medications, foodstuffs, or by a variety of infections. Unfortunately there are no skin tests or blood tests which can indicate which of these possible causes may be responsible. Usually infections and medications can be excluded as a cause by your doctor. In the vast majority of patients all investigations performed are entirely normal and no detectable cause for the urticaria can be found.

To try to establish whether food/drink may be responsible for the urticaria the only practical approach is to keep a food diary, i.e. keep a written account of what has been eaten for about a month. Then go back through the month and try to establish a relationship between attacks of urticaria and particular foods/drinks taken during the previous 24 hours. If it is possible to find a suspect food/drink then cut it out completely for a further month and see what happens. Usually it is impossible to find a responsible foodstuff unless it is very obvious right from the start. Very occasionally special exclusion diets (e.g. exclude all dairy produce) are of some help but these should only be performed with the help of a professional dietitian.

In most patients the cause of their urticaria is never discovered but as time goes by the condition gradually disappears anyway. During the period that it takes to go away many of the symptoms can be controlled by taking antihistamine tablets. These tablets are very safe and can normally be taken for prolonged periods if necessary (double cheek with your doctor if you might be pregnant).

They sometimes have the side effect of drowsiness and can also interact with alcohol. Patients taking antihistamines should be extra careful when operating any form of machinery (especially driving a car) and should never do so if they have also been drinking any alcohol.

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Psoriasis

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Psoriasis is a common condition with an inherited susceptibility in which the exact cause remains unknown. It is not a skin infection and cannot be 'caught by' close contact. Psoriasis is not associated with any internal abnormality of the body. About 2% of the population are affected and this percentage chance of developing the condition is increased if there is a family history of the disorder. For example, if you have psoriasis then the chances of your children developing psoriasis is increased above 2% because they will have inherited the tendency to psoriasis from you. The exact likelihood of your children developing psoriasis is not known, but is probably less than 1 in 10. This likelihood increases if both parents have psoriasis. If you have inherited the predisposition to psoriasis then a wide variety of precipitating factors can bring out the condition. These factors include stress (such as death in the family), other illness (such as tonsillitis or hospital admission), and certain drugs. In many patients there is no obvious reason for the appearance of the psoriasis. Psoriasis is not related to diet or to environmental factors such as changes in washing powder, etc.

The typical skin lesions are red, scaly patches varying in size from 0.2 cm to several centimeters in diameter. These scaly patches can affect any site; most commonly the elbows and knees are involved. The scalp is another common site. The nails may become pitted or discolored. The condition tends to wax and wane, sometimes going into spontaneous remission (perhaps for prolonged periods). On other occasions psoriasis seems to go through active periods when it may be particularly difficult to control with treatment. These different phases which the disease might go through can last anywhere from a few weeks to some months.

In other words, if your psoriasis is at present going through an active and troublesome phase, this does not indicate that your psoriasis will always be active; usually it will gradually settle down again with some intensive treatment. Some patient's psoriasis does not go through these phases but, if left untreated, would remain about the same for long periods. Almost all patients with psoriasis remain in otherwise excellent health. Psoriasis is not a sign of any internal abnormality and is not associated with any serious threat to your general health.

The main aims of treatment are to control the activity of the disease, especially during the bad periods, and reduce the patches to the smallest possible size. It is usually possible to make the patches disappear completely with regular daily treatment. To get the patches to go away may take several weeks of regular treatment and it is very important to persevere and 'get on top' of the condition. It is very important that you dominate the psoriasis and not allow the psoriasis to dominate you. This can usually be accomplished with the help of your Dermatologist.

Treatment is usually with topical applications. The word 'topical' means something that is applied to the surface of the skin such as tar or dithranol. Occasionally systemic treatment' is required for particularly severe disease. 'Systemic' means taking something by mouth to act upon the skin from the inside. Systemic treatment has side effects and is only used as a last resort.

Treatment with tar and/or dithranol topical applications are the best treatments for psoriasis. This is because we know that persistent treatment with these things will lead to improvement in nearly every case. The word 'persistent' is very important because if the treatment is only applied halfheartedly (for example, only twice per week), then the chances of success are very much reduced. Tar and dithranol treatments have several important advantages over other treatments for psoriasis such as corticosteroid creams. These advantages include no development of resistance to treatment and no serious side effects. These two properties are very different to corticosteroid creams which can have important side effects on the skin and can also lose their effectiveness as time goes by when the disease gets used to the corticosteroids. If you use corticosteroids for prolonged periods and your psoriasis becomes resistant to their effects, then you will need stronger and stronger corticosteroid creams to control the disease, leading to a vicious circle situation. A further important advantage of tar and/or dithranol over other treatments is that once the psoriasis is under control with tar or dithranol, the tendency for the disease to remain quiet for prolonged periods is much greater. In other words the 'rebound effect' when treatment is stopped is much less than with steroid-type creams.

Both natural sunlight and artificial sunlight treatment may lead to considerable improvement but you should be wary of artificial sun beds and ask a Dermatologist's advice before starting treatment.

There is no known 'cure' for psoriasis (though psoriasis is at the centre of many skin research programmes) and all available treatments are effective for only a temporary period. Sometimes that period can be many months or years during which no further treatment may be needed. If and when the psoriasis becomes active again, the same treatments can simply be used again. There is no resistance to the beneficial effects of tar and dithranol which are the two best treatments for the condition. There are certain situations in which corticosteroids are definitely indicated for psoriasis and under these circumstances this type of treatment can be very good. Usually steroids should be used for only 2 - 3 weeks in this way. 1 hope this summary has helped you to understand something about the disease known as psoriasis. You are very welcome to ask me to clarify any points or questions when you next see me.

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Acne

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The full medical term is 'acne vulgaris' and this is one of the commonest conditions which Dermatologists are asked to see. In fact, the condition is so common that some Dermatologists believe that almost everyone suffers from acne at some stage during their early adult life. Usually only those individuals with a significant form of the condition require treatment from their Family Doctor or Dermatologist.

The condition is characterised by blockage and inflammation of the hair follicles and associated sebaceous (natural oil producing) glands of the face, chest and upper back. Appearances vary from mild greasiness of the skin together with some blackhead (or 'comedone') formation to severely inflame cysts in rare cases. Sometimes blackheads do not appear but blockage of the sebaceous glands leads to the formation of 'whiteheads' (or 'closed comedones') instead. These are very small white or skin-coloured spots. Inflammation of either form of comedone will lead to the appearance of typical inflamed acne spots.

The aim of the treatment is to reduce the overall numbers of comedones and to reduce the likelihood of the different types of comedones from turning into inflamed spots or cysts. Treatment is a combination of 'topical' agents (things which are applied to the outside surface of the skin) and (systemic' agents (things which are taken by mouth to act on the skin from within). It is very important that you understand that no form of treatment will be fully effective in less than twelve weeks. You must persist with regular treatment for the whole period before seeing any response. Tablets are often much more effective if they do not mix with food in the stomach. Your stomach will be empty two hours after your last meal or drink containing milk. You should not take anything other than water for 40 min after your tablets. You may need to find four times during the day (depending on what dose of treatment you are on) during which these rules can be followed; two helpful times are before breakfast and before going to bed.

The topical applications are not intended to treat inflamed red spots, they are designed to prevent the progress of comedones into spots. Therefore, think of them as treatments which work by preventing spots from developing. In other words do not stop using the preparations too soon after improvement, the treatment is probably still working at this stage. Continue for the full period, as directed by your Doctor. You need to apply these topical agents to the whole of the potentially affected area which has been giving you problems (e.g. the whole of the cheeks, chin and chest), whether there are spots present or not!! Obviously there is no point in applying anything to an area which has never been involved with your acne. These topical treatments will nearly always lead to some redness and dryness of the skin when you first start the application. This will gradually settle down. To help your skin get used to this irritation you should start off by leaving the application on for only twenty minutes initially, and then washing it off thoroughly with soap and water.

After one week of this you can increase to 30 - 60 minutes, depending on how well you can tolerate the treatment, and then double the length of time each week until you can leave it on for eight hours overnight. Beware because the treatment has a mild bleaching effect on clothing and can turn dark clothing (including bed clothes) lighter.

It is perfectly all right for you to apply moisturising creams to counteract the drying effect of the treatments, and also you are entirely free to apply makeup as you wish, neither of these things will worsen your acne.

The treatment for acne is designed to keep the skin condition under control until the body's own tendency to get rid of acne has occurred (usually between 20 and 30 years of age). Most treatments for acne can be continued for prolonged periods safely until this natural improvement begins.

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Rosacea

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This is a very common condition of adult life. The face and nose are the commonest sites. Redness, some swelling, a feeling of fullness or burning, and a tendency to flushing are the main features. Some patients get spots a bit like acne. Many patients find that certain precipitating factors can be identified and avoided. Typically these include - alcohol, heat, hot drinks, spicy food, direct sunshine, etc. Oral medication is often very helpful. Some patients need surgical treatment for tissue swelling if this is severe. Other patients need laser surgery to remove dilated blood vessels. Most patients can be kept under good control.

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