Skin allergies can get quite uncomfortable, and often leave unsightly traces on the skin.
ALTHOUGH many people are concerned about the appearance of the skin, which is the largest organ in the body, it is often forgotten that the skin performs several vital body functions. These include protecting the body from harmful substances in the external environment, playing an important role in temperature regulation, and manufacturing vitamin D, which is essential for the growth and maintenance of bone.
There are several types of dermatitis, which is an inflammatory condition of the skin. The skin is red, dry, thick, cracked and blistered in the mild form and broken, raw and likely to bleed in the more severe form.
Atopic dermatitis is thought to be inherited as it often occurs in families. It is associated with other allergic conditions like asthma and allergic rhinitis.
Contact dermatitis occurs when there is contact with a particular substance that causes the skin to become inflamed. There are two types, i.e. allergic and irritant contact dermatitis.
The former is due to an allergen which causes an abnormal reaction of the body’s immune system. After initial exposure to an allergen, the body is sensitised to it and it causes a reaction on every occasion there is contact with the allergen. During the allergic reaction, the normal cells and tissues of the skin are attacked as well as the allergen.
The latter is due to contact with an irritant, which is a substance that damages the skin, causing it to be inflamed. Any person who is exposed to irritants for a sufficient period of time can get irritant contact dermatitis.
Allergic and irritant contact dermatitis can occasionally occur simultaneously.
Contact dermatitis more commonly occurs in females. The irritant type is more common than the allergic type as it accounts for the majority of cases. The hands are affected in about three quarters of all cases. There is no particular age preponderance.
Allergens and irritants
Common allergens include cosmetic products, e.g. fragrances, nail varnish, hair dyes; metals, e.g. nickel or cobalt found in jewellery; rubber; clothing, especially the dyes and resins; adhesives, e.g. epoxy; certain plants, and some pharmaceutical topical applications.
Common irritants include soaps, detergents, perfumes, solvents, abrasives, acids, alkalis, cement, dust, soil and some plants.
The risk of exposure to irritants is increased in certain occupations, like beauticians, cleaners, construction workers, housekeepers, hairdressers, healthcare professionals, painters, and printers. Contact dermatitis, especially the irritant type, may be aggravated by heat, cold, low humidity, and friction.
The skin is red, dry, thick, cracked, and blistered. The hands and the face are the usual sites affected. There are additional feature(s) depending on whether it is the allergic or irritant type.
In the case of the former, there is itchiness of the part of the skin that came into contact with the allergen, and occasionally, other parts of the skin too. The itchiness may appear hours or days after contact with the allergen.
In the case of the latter, there is a burning sensation and soreness that appears within two days after exposure to the irritant. It only affects the part of the skin that came into contact with the irritant.
Bacteria can infect the skin in contact dermatitis, especially if the skin is cracked or there is scratching. The skin is redder, feels hotter, oozes fluid, and crusts may form. Quality of life may be affected, especially if there are severe symptoms or the condition is chronic. It may lead to psychiatric conditions, e.g. depression, anxiety.
The identification of the allergens or irritants is crucial to the management of contact dermatitis. Once identified, measures can be taken to avoid them. Even if it is not possible to avoid the allergen or irritant because of one’s occupation, the risk can be reduced considerably by wearing protective clothing.
The family doctor may make a referral to a skin specialist (dermatologist) if the allergen or irritant is not identified or the response to treatment is inadequate or absent.
The primary method of identification of allergens or irritants is the patch test. Small amounts of substances are attached to the back with a non-allergic tape. The patches are removed after 48 hours and the skin checked for any reaction. Another check may be made a few days later for delayed reactions.
Treatment is usually effective. Some patients may find that their symptoms disappear or there is partial improvement in about 80% of patients.
Emollients are compounds that soften the skin, making it supple and moist, thereby preventing additional irritation of the dry and cracked skin.
There are different types of emollients. The type prescribed is dependent on the degree of skin dryness, the area of skin affected, and the patient’s preference. Creams and lotions are suitable for red, inflamed areas, and ointments for dry skin that is not inflamed.
Some patients may have to use different emollients before finding one that is effective. Different emollients may be used, i.e. one when the symptoms are mild, and a different one when they are severe. Different emollients may also be needed for the hands and the face.
After washing the affected skin, it should be dried gently before applying the emollient. It is important to avoid rubbing the emollients in as this can irritate the skin. The emollients are to be applied as advised by the doctor.
Some people experience side effects from emollients, the most common being a rash. It is advisable to apply a small amount at the initial application before applying to a bigger area. This will enable one to check whether the skin will react to it. If there is a reaction, the doctor should be consulted and an alternative emollient will be prescribed.
Some emollients contain paraffin, which is combustible. As such, they should not be applied near a naked flame or when one is smoking.
Topical corticosteroids are also prescribed if the skin is very inflamed and sore (to reduce the inflammation). These medicines are safe and effective if used correctly. The dosage depends on the severity and location of the dermatitis, e.g. mild corticosteroids for the face, eyelids and children. It would be prudent to adhere to the doctor’s advice on the frequency of application of topical corticosteroids.
As a general rule, the emollient should be applied first and the topical corticosteroid several minutes later to allow time for the emollient to be absorbed by the skin.
Tretinoin is prescribed by the dermatologist if there is failure to respond to treatments like topical corticosteroids. This medicine, which is taken orally, reduces the irritation and itchiness.
Tretinoin should never be taken by pregnant women as it can cause severe birth defects. It should also not be taken by breastfeeding mothers as it can get into breast milk and cause harm to baby. Its prescription in women of reproductive age is not recommended. Such prescription is only done under very stringent conditions, i.e. adequate contraception, preferably two methods; pregnancy tests prior to commencement and during treatment; and informed consent of the patient.
The side effects of tretinoin include flushed skin, dry skin, headaches, red eyes, pain in the muscles and joints, hair loss and vision problems. Treatment should be stopped immediately upon the onset of vision problems and the dermatologist should be consulted.
The most effective way in preventing contact dermatitis is to avoid contact with allergens or irritants. As this is not always possible, certain measures can be taken, including:
> Washing the skin as soon as possible after contact with an allergen or irritant.
> Using protective clothing, e.g. gloves.
> Substitution of products containing allergens or irritants with alternatives that do not contain the allergens or irritants.
> Repeated application of emollients.
■ Source: Dr Milton Lum