Contact Dermatitis

Contact dermatitis is the most frequent occupational skin disease. It is caused by exposure to a wide range of irritants or allergens in the workplace or at home. This includes over-exposure to water, ’wet work,’ and hand cleansers, and environmental irritants such as heat and sweating. It is difficult to separate irritant contact dermatitis from allergic causes by clinical or histological features. However, the presence of irritant dermatitis increases the risk of also developing a contact allergy.

The condition most commonly presents as an erythematous rash with itch and scaly features. However, the appearance of contact dermatitis can be highly variable and include urticaria, blisters, fissuring, or pigmentation changes. The rash occurs at a site of contact with the irritant or allergen with the majority of cases involving the hands. The damage to the skin could be caused by either once-only exposure to a high concentration of a highly irritating chemical. This type of reaction will occur in most people with sufficient exposure. However, the more frequent cause is repeated exposure to weaker irritants. Cumulative irritant contact dermatitis from repeated mild skin irritation can take from several months to several years to develop. This type of reaction is more likely to occur in people with sensitive skin.

Management of contact dermatitis

Management of all forms of contact dermatitis should involve:

• Tailoring treatment according to the severity and morphology of reaction and the body site(s) involved;
• Assessing for and addressing the contribution of irritants, allergens, and endogenous dermatitis to the clinical problem;
• Evaluating work, home, and play environment exposures; and
• Reviewing all topical preparations (e.g. prescribed, over-the-counter and alternative medicines, cosmetics, and personal care products) used regularly or intermittently for irritant and allergic potential.

General principles for treatment of dermatitis include:

• Avoiding irritants and allergic factors; and
• Topical treatment.

Only very small amounts of a chemical are required to cause severe allergic contact dermatitis. Therefore, the best management for contact dermatitis is to avoid those allergens or irritants causing the rash including soap, shampoo, and latex gloves. Whenever this is not possible, contact with them needs to be reduced using substitute products or properly selected protective gloves. Rubber or polyvinyl chloride (PVC) gloves are good alternatives for general purposes. However, nitrile gloves are recommended for healthcare personnel who require a high level of protection against infectious agents.

Many people who develop a reaction to gloves have non-allergic contact dermatitis. Although this condition is not immune-mediated, ongoing exposure can increase the risk of developing a latex allergy as damage to the barrier properties of the skin may allow absorption of latex. Removing gloves on a regular basis is beneficial, particularly if dermatitis is already present as sweating and friction can aggravate the condition.

Patients with atopic dermatitis should especially avoid ‘wet work’ and contact with irritants because atopic dermatitis is significantly associated with irritant contact dermatitis. A formal patch testing may be useful in identifying the irritants causing the rash.

Patch testing may be used:

• To confirm diagnosis of a contact allergic reaction and the suspected allergen;
• When hand or face dermatitis is persistent or recurrent;
• When an otherwise unexplained deterioration or change in pattern, extent, or severity of a long-standing presumed irritant contact or endogenous dermatitis occurs;
• When dermatitis fails to respond to previously effective treatment strategies; and
• To identify the allergenic component in a multicomponent substance such as a cream.

Measures used to relieve itching include patting or pressing the skin and cooling the skin with water, followed by the application of soothing emollients. Soap and shampoo substitutes such as Cetaphil^®, DermaVeen^®, and QV^® Wash should be used, and an emollient applied immediately after washing.

Topical treatment

Corticosteroids are the main topical treatment for contact dermatitis. For the initial treatment of contact dermatitis of the face and flexures, the following therapies may be considered:

Hydrocortisone 1% cream or ointment topically, once daily

Or

Desonide 0.05% lotion topically, once daily

These agents are typically applied for up to a week until the skin is clear. Once resolution of symptoms occurs, an emollient may be used to prevent recurrence.

In severe acute cases, oral corticosteroids may be required. Only a short course is generally needed to settle the contact dermatitis once the allergen or irritant has been removed. The Therapeutic Guidelines recommend slow tapering of oral corticosteroid doses to prevent rebound.

Prednisolone 25mg to 50mg (0.5mg/kg) orally, once daily for 5 to 7 days then taper over 2 weeks.

Understanding the causes of contact dermatitis is important in order to develop strategies for prevention. Ideally, skin care advice should be incorporated into hand hygiene education in workplaces. Skin cleansers containing allergens should be substituted, and accelerator-free gloves recommended.