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Eamonn Brady, MPSI, Whelehans Pharmacies, Mullingar, Co Westmeath
There are many causes of dry skin, among the most common are conditions like dermatitis, eczema, psoriasis, and seborrheic dermatitis.
The simple definition of dermatitis is inflammation of the skin. Different types of dermatitis include contact dermatitis, seborrheic dermatitis (dandruff), and atopic dermatitis (eczema). Symptoms include swollen, reddened and itchy skin. About 80 per cent of dermatitis cases are ‘contact dermatitis’, caused by an allergic response to a substance with which skin has been in contact. This can include latex, detergents, or jewellery such as nickel. Symptoms are often mild. Treatment involves avoiding contact with the offending substance. Skin hydration with an emollient is important (more details below). A topical steroid such as hydrocortisone 1 per cent cream may be required.
Eczema, a type of dermatitis called atopic dermatitis, is a chronic inflammatory skin condition that involves a complex interaction between environmental and genetic factors. It generally starts in childhood, with many growing out of it. Eczema affects over 20 per cent of children and one-in-10 adults in Ireland. It is often hereditary and there is an association with asthma and hay fever. Eczema has become more common in recent years; the cause of this is uncertain. There are theories such as the ‘hygiene theory’, which is discussed in more detail later in this article. Skin hydration can control eczema and in more severe cases, steroid creams may be temporarily required.
Psoriasis affects between one-and-100 to three-in-100 of the population. It is caused by inflammation of the skin. It typically develops as patches of red, scaly skin. Plaque psoriasis is the most common type of psoriasis (about 80 per cent of cases). Symptoms are dry, red skin lesions, known as plaques, that are covered in silver scales. They normally appear on the elbows, knees, scalp, and lower back, but can appear anywhere on the body. The plaques are normally itchy, sore, or both. In severe cases, the skin around the joints may crack and bleed. Appropriate treatment will keep psoriasis under control, but there is not a definitive cure. Skin hydration is important; other treatment options for more severe psoriasis include topical steroids, topical vitamin D analogues (ie, Calcipotriol), and coal tar preparations.
Seborrhoeic dermatitis is characterised by red, scaly patches that develop on the scalp, face, and upper trunk. It is more likely to affect men than women. It is often aggravated by changes in humidity, changes in seasons, trauma (ie, scratching), or emotional stress. The usual onset occurs with puberty. It peaks at age 40 years and is less severe in older people. Approximately 1-to-3 per cent of adults suffer from seborrhoeic dermatitis. Dandruff is a mild form of seborrhoeic dermatitis and is estimated to affect 15-to-20 per cent of the population.
The cause of seborrhoeic dermatitis is unknown. There is evidence that a type of fungus called malassezia has an influence. Seborrhoeic dermatitis most commonly affects the sides of the nose and the nasolabial folds (skin folds that run from each side of nose to corner of mouth), eyebrows, glabella (space between eyebrows and above the nose), and scalp. There are many treatment options for seborrhoeic dermatitis. Shampoos containing anti-fungal agents like ketoconazole or ciclopirox appear to be the most effective in the control of scalp seborrhoeic dermatitis, including dandruff.
‘Hygiene hypothesis’ and autoimmune conditions
The ‘hygiene hypothesis’ is a theory that lack of exposure in early childhood to infectious agents means that the child’s immune system has not been activated sufficiently during childhood. This lack of exposure is down to our super-clean world of modern living, including antibacterial washes, vaccinations, and general sterility where children are not exposed to germs in a similar manner to previous generations of children. The theory hypotheses that because the immune system is ‘not activated’ during childhood, this leads to the immune system becoming over-sensitive to common substances such as pollen, dust-mite, and animal fur, leading to the higher incidence of autoimmune conditions like asthma, hay fever, and eczema in recent years.
One of the first scientific explanations of this theory was by a lecturer in epidemiology from the London School of Hygiene and Tropical Medicine, David P Strachan, who published a paper on the theory in the British Medical Journal in 1989. He noticed that children from larger families were less likely to suffer from autoimmune conditions like asthma and eczema. Families have become smaller in the Western world over the last 40 years, meaning less exposure to germs and infections; it is over the same period that health authorities have seen an explosion in autoimmune conditions such as asthma and eczema. Further studies have been conducted since then, supporting the theory.
In adults, food allergies or food intolerance do not appear to be a factor in dry skin conditions such as eczema and psoriasis, so avoiding certain foods is not of any benefit. In infants, avoidance of certain foods can be helpful, but professional guidance is important. Common food triggers include eggs, nuts, peanut butter, chocolate, milk, seafood, and soya.
Maintaining adequate skin hydration
Evaporation of water on the skin leads to dry skin, especially in people suffering from dry skin conditions, such as dermatitis, eczema, or psoriasis; skin hydration is a key component of their overall management. Thick creams (ie, Diprobase), which have a low water content, or ointments (ie, petroleum jelly, emulsifying ointment), which have zero water content, will better protect against dry skin than lotions. Hydration is best applied immediately after bathing, when skin is hydrated. Improve hydration by soaking in a bath containing a bath additive such as Oilatum for 10-to-20 minutes. Moisturisers and emollients are discussed in more detail below.
Use of steroids
Topical corticosteroid such as hydrocortisone 1 per cent cream may be prescribed by a GP (or OTC from pharmacy) for many dry-skin conditions. The face and skin folds are areas that are at high risk of thinning and marking with corticosteroids, so care and moderation are important. The GP may prescribe more potent corticosteroid creams, such as clobetasone 0.05 per cent (ie, Eumovate), betamethasone 0.01 per cent (ie, Betnovate), or clobetasol 0.05 per cent (ie, Dermovate) for short periods during bad flare-ups.
In relation to potency, topical corticosteroids are classed as follows:
Corticosteroids, especially the more potent versions, should be used for the shortest period possible and use of the most potent ones should be under strict medical supervision. The patient may need to be referred to a dermatologist in more severe cases.
When using a corticosteroid and a moisturiser, it is good practice to use the corticosteroid first and to put on the moisturiser after half an hour to allow the skin time to absorb the corticosteroid. In more severe cases, treatment may include tacrolimus (Protopic ointment) for eczema or UVB phototherapy and psoralen plus ultraviolet A (PUVA) therapy for psoriasis.
Therapies with no evidence-base
Supplementation with essential fatty acids, pyridoxine, vitamin E, multivitamins, and zinc salts has no proven value. Reactions to washing powders are rare and avoidance of biological washing powders is of no benefit.
Moisturiser and emollient therapy (more detail)
No matter what type of dry skin condition, keeping the skin well moisturised is key to managing the condition. Using moisturisers and emollients is key.
Pat-dry the skin gently. Avoid scrubbing skin with a towel.
How and how often to use moisturisers
Moisturise skin immediately after washing while it is still damp; it is more effective when applied at this stage. The more often one moisturises their skin, the more effective moisturisers are. There is no limit to the number of times that one can apply a moisturiser. Always apply moisturisers in a downward motion, in the direction of hair growth. Gently massage it into the skin. Apply enough to moisten the skin without leaving it greasy. To help remember to apply it, keep samples in various locations at home, at work and in a bag or pocket. Choose one that feels comfortable. Always avoid perfumed products.
Run a lukewarm water bath. Put two tablespoons of emulsifying ointment into a jug of almost-boiling water. Whisk into creamy froth and add to bath water. Emulsifying ointment makes the bath slippery, so caution is needed when getting in and out of the bath. Emulsifying ointment can be kept soft by storing it in the hot press. Stay no longer than 10 minutes in the bath. Pat skin dry afterwards and if prescribed steroidal skin cream, apply to the affected area then wait 10-to-15 minutes and apply moisturiser in a downward motion.
Practical advice to manage dry skin conditions
References on request
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