Contact Dermatitis

The diagnoses of dermatitis includes all forms of inflammation of the skin and can be broadly divided into irritant and allergic forms. An overview of the causes and management of this common condition.

• Contact dermatitis accounts for 47% of dermatological consultations

• It is a eczemous reaction caused by external agents

• Practice nurses can improve patient compliance with lifestyle modification measures.

Most healthcare professionals have had some experience of contact dermatitis. It is one of the most common public health problems and accounts for up to 47% of dermatological consultations.

Despite this, there is enormous confusion about the causes of this distressing condition and how to prevent it. Recognition and avoidance of irritants is an essential part of treatment and, in the long term, could mean the difference between an adult patient being able to continue in their present occupation or having to change career.

In addition, patients and parents are becoming increasingly aware of the role of environmental irritants in skin conditions. They are asking questions about avoidance, whether or not they already suffer from any form of dermatitis. Practice nurses are ideally placed to discuss lifestyle factors and general preventative measures with patients.

The diagnosis of dermatitis is often used interchangeably with that of eczema, although technically it covers a broader spectrum, including all forms of inflammation of the skin.

Dermatitis can manifest itself with any combination of:

• itching of the skin

• redness and tenderness of the skin

• scaling of the skin

• clustered papulovesicles.

Contact dermatitis is an eczematous reaction caused by external agents. The causes can be broadly divided into:

• primary irritant contact dermatitis (ICD), in which irritant substances have a direct toxic effect on the skin

• allergic contact dermatitis, where immune hypersensitivity is stimulated by contact with an allergen.

PRIMARY ICD

A reaction of the skin to external injury is referred to as primary ICD. The condition is usually caused by simple skin irritation, and less than one-fifth of such involvement is caused by allergy.( n1)

Patients with a history of atopy (eczema, asthma, hay fever) are more susceptible to the effects of primary irritants, but they are not the only ones at risk.

The most common irritants found in the environment are:

• soaps

• detergents

• water

• solvents

• cement

• a dry atmosphere.

The ICD reaction tends to occur on exposed surfaces and more often on thin skin, for example on the dorsum of the hand, rather than on the palm. Acute lesions are weeping, acutely painful and vesicular. Chronic lesions tend to manifest as thickened, dry, cracked skin.

There are many factors that determine the development of symptoms of ICD:

Vulnerability of the skin

Thin skin -- such as the face, the groin and to a lesser extent, the hands -- is more prone to damage from irritants.

Age

The immature skin of infants and the thin, cracked skin of the elderly is particularly prone to irritant dermatitis.
Exposure to wet or very dry conditions

Patients whose occupation involves frequent and prolonged immersion in water -- including cleaners, hairdressers and chemical workers -- may have macerated skin that is more susceptible to irritation.

Amount of contact

Hands are more frequently exposed to occupational irritants than other areas of the body, for example when handwashing clothes. However, significant irritation can result from relatively minor irritants if they are in contact with the skin for prolonged periods. Washing detergent residue on clothes is an example of this.
Sources of irritation

Some ICD has an obvious cause, for example a hairdresser's apprentice who has developed hand dermatitis since coming into contact with perming solutions. Other sources may be more difficult to identify. In these cases, the patient should be given general advice about avoidance of primary irritants, and referred to the GP for specific treatment and dermatology referral if appropriate. The skin can also be worn and irritated by cold and heat, scratching, pressure or friction.

Degree of irritation

An irritant is defined as a chemical that in most people is capable of producing cell damage if applied for a sufficient time and in a sufficient concentration.

It is self-evident that an industrial solvent in concentrated form will cause more cell damage than the same solvent in diluted form. Nonetheless, patients may underestimate the excess risk they are putting themselves at by failing to wear adequate skin protection when diluting such products before use.

Type of product used

In laundry detergents, for example, the incidence of contact dermatitis reactions to some granular laundry detergents may be up to 0.7%. However, some manufacturers have invested considerable research into producing detergent components with low skin sensitisation levels.

ALLERGIC CONTACT DERMATITIS

Allergic contact dermatitis (ACD) is less frequent than primary ICD, and is much more common in atopic individuals (with family history of asthma, eczema or hay fever). In the general population, the most common allergens giving rise to ACD include:

• nickel

• rubber

• fragrances

• acrylic

• topical medications (such as neomycin)

• chromium/chromates (in cement etc)

• plant allergens

• formaldehyde and other biocides

• hairdressing chemicals

• dyes (eg in shoe leather)

Products of low molecular weight penetrating the skin cause ACD. These sensitise the T-lymphocytes, which travel throughout the body. This results in future contact with the allergen -- on any part of the body -- causing a local allergic reaction one to three days later.

Factors that affect the development of ACD include:

• degree of atopy -- in other words, degree of hypersensitivity of the immune system

• the concomitant presence of ICD --which probably facilitates the penetration of allergens into the skin, by causing inflammation and cracks in the surface skin barrier

• the type of fragrance used -- epidemiological studies have described an increasing prevalence of fragrance allergy, and indicated an association with hand eczema, but studies suggest wide variation in the allergenic potential of different fragrances.

MANAGEMENT OF CONTACT DERMATITIS

For both primary irritant and allergic contact dermatitis, avoidance of exposure to the irritant or allergen is the mainstay of treatment. Management might include the measures outlined below.

Occupational measures

In the example given earlier of the hairdressers the apprentice could wear gloves or avoid those tasks that involved contact with the perming solution.
Barrier measures

Wearing gloves is an example of a barrier measure (preferably non-allergenic) when handling any potential irritants.

Product selection

Select products less likely to cause irritation such as using washing powders with proven low irritation level.

Industry measures

A good example is of an industry reducing the level of common irritants is in construction. This industry results in up to 20% of consultations for dermatitis but in Scandinavian countries, the addition of ferrous sulphate to cement has virtually eliminated the use of chromium and has reduced its allergenic potential enormously.( n8) As a consequence, the recently built bridge and tunnel between Sweden and Denmark resulted in no new cases of ACD from chromium.

This should be compared to the British experience, where a comparable project (the building of the Channel Tunnel) was associated with a number of new cases of ACD.

Emollients

The liberal use of emollients can provide a protective barrier to allergens, as well as reducing cracking. Cracked skin offers far less protection against penetration by allergens or irritants, and can also predispose the skin to secondary infection with bacteria such as staphylococcus aureus.

EDUCATION

The aims of any treatment regime for dermatitis or eczema should be to:

• replace moisture in the skin

• provide a waterproof barrier to minimise further water loss

• reduce inflammation

• improve quality of life.

The rationale for using of emollients should be explained. Patients may be relatively unwilling to use emollients with great frequency, because of cosmetic unacceptability and perceived lack of efficacy when compared to topical steroids. However, topical emollients are safe and extremely effective at hydrating the skin, and forming a waterproof barrier to minimise further water loss. Their effect is, however, short-lived, and patients should be encouraged to reapply them at least 3-4 times a day.

Patients should also be advised to use emollients as the mainstay of treatment, regardless of concomitant use of topical steroids.

The practice nurse also has a role to play in explaining the relative risks of topical steroids, of which many patients are wary. In fact, use of topical steroids in contact dermatitis is likely to be limited to a relatively small area, and the likelihood of side-effects is very small.

The practice nurse is also in an excellent position to discuss lifestyle factors that may influence the development of dermatitis. Such discussions can be opportunistic, when the patient with a history of contact dermatitis presents for a general health check, as well as specific to skin-related consultations.

The importance of avoiding potential irritants and allergens should be stressed.

SUMMARY

Contact dermatitis can be broadly divided into irritant and allergic forms. However there is overlap between the two and management is broadly similar.

Patients may be reluctant to comply with long-term lifestyle modification measures such as allergen avoidance and regular use of emollients. The practice nurse is well placed to give them the information they need to improve compliance.

LOCAL AND SYSTEMIC SIDE-EFFECTS FROM TOPICAL STEROIDS

Factors affecting the level of local and systemic side-effects from topical steroids include'
Thickness of skin

• skin of the face, neck and groin is particularly thin
The age of the patient

• the skin of the very young and the very old is thinner
The frequency of application

• this may be reduced between exacerbations
The strength of the topical steroid

• it is worth considering limiting the use of potent topical steroids to severe exacerbations
The size of the area to which topical steroids are applied
The length of treatment

• many patients can stop using topical steroids once an acute exacerbation has resolved, but should be encouraged to continue to avoid precipitating factors and to use emollients liberally.

Last updated Jan 4/07