Allergic contact dermatitis and photoallergy

Management Strategy

Identification and avoidance of offending allergens and potential cross-reacting agents is the principal management strategy for ACD. Patch testing is the gold standard for diagnosing ACD and identifying allergens. Following this, patient education regarding the diagnosis, the relevant allergen(s), and how to avoid them, is essential.

Government legislation can reduce ACD rates significantly. The European Union has introduced legislation to limit the concentration of the preservative methylisothiazolinone (MI) in personal products, to restrict nickel content in jewelry, and to reduce available chromate in cement by adding ferrous sulfate. These measures have resulted in reduced sensitization rates and a reduced number of cases of ACD to MI, nickel, and chromate, respectively.

The workplace also plays an important role in minimizing exposure to allergens, thereby reducing rates of sensitization and ACD. This can be done by modifying work environments; for example, by improving ventilation to reduce exposure to airborne substances, by substituting common allergens, and by providing and ensuring the use of appropriate personal protective equipment (PPE).

Glove use is an important component of ACD prevention and management. Glove choice will depend on the activity being performed and on the chemicals being handled. When working in a hot environment, sweating and leaching of chemicals from gloves can occur. Cotton gloves can be worn underneath rubber or leather gloves to prevent sensitization to rubber accelerators and chromate.

The initial management of ACD follows the general principles of eczema therapy. This includes avoiding skin irritants (such as water, soap, friction, and heat), using emollients or moisturizing creams, and applying topical corticosteroids to affected areas. Barrier creams have had limited success in preventing dermatitis. Topical tacrolimus and pimecrolimus have been shown to be effective. In severe cases, oral corticosteroids may be required. These are usually short courses of prednisolone 25–50 mg daily for 1 week.

If secondary infection is suspected, oral antibiotics (cephalosporins, erythromycin, or flucloxacillin) or topical antibiotics (mupirocin or fusidic acid) may be required.

ACD will usually resolve with this initial treatment, provided that the responsible allergen has been identified and avoided. However, patients may experience ongoing issues if they are inadvertently exposed to the allergen or if they develop persistent postoccupational dermatitis, a dermatitis that recurs despite absence of exposure to causative agents.

If ACD is chronic or refractory to first-line treatments, ultraviolet light therapy with narrowband ultraviolet B (UVB) or psoralen plus ultraviolet A (PUVA) can be used. Systemic immunosuppression with ciclosporin, azathioprine, and methotrexate may be considered. Acitretin may be helpful in some cases, particularly if there is hyperkeratotic palmar involvement. Alitretinoin is helpful in cases of chronic hand eczema; however, more evidence is required to determine its usefulness in treating ACD specifically.

Small case series and a retrospective chart review have suggested that dupilumab is effective in treating ACD. A phase 4 clinical trial is underway to investigate the effects of dupilumab on ACD in 20 patients.

Recent evidence suggests that there is an association between contact dermatitis and smoking. There is no strong evidence available to show that smoking cessation leads to improvement of ACD. However, smoking cessation could be a worthwhile action, especially when considering health cobenefits.

For PACD, identification and avoidance of the photoallergen is again the major treatment goal. Sun protection, with sunscreen and protective clothing, is also important. If the photoallergen is an ingredient in sunscreen, avoidance and substitution of that ingredient is recommended. Physical UV blockers such as zinc oxide or titanium dioxide are not known to cause allergic or PACD and may be useful substitutes to chemical sunscreens.