Allergic contact dermatitis

Essentials

  • It is often not possible to differentiate allergic contact dermatitis from other types of dermatitis on the basis of clinical presentation alone.
  • The diagnostic cornerstones are clinically established eczema, contact allergy and temporally-related exposure to the allergen in question.
  • The possibility of allergic contact dermatitis should be borne in mind where dermatitis is not resolving despite appropriate treatment.

Aetiology

Symptoms

Diagnosis

Investigations

  • Patch testing is usually not indicated if the history clearly identifies the causative allergen, for example nickel.
  • The diagnostics of skin contact allergy and allergic dermatitis use epicutaneous tests (patch testing (Diagnostic tests in dermatology)) Dynamed, which demonstrate possible sensitisation to allergens.
  • However, a positive test result does not always prove the causal relationship with the patient’s dermatitis.
  • Testing is carried out and interpreted by a dermatologist.

Treatment

  • The definitive treatment of allergic contact dermatitis is the avoidance or removal of the allergen (personal protective equipment, changing substances or methods used at the workplace, change of employment).
  • Topical glucocorticoid creams
  • Systemic treatments for eczematous conditions are used in chronic and difficult cases at the discretion of a dermatologist.

Topical treatment

  • Treatment of allergic contact dermatitis in hands: see (Hand dermatitis).
  • Moderately potent to potent glucocorticoid creams Dynamed once or twice daily until the skin has healed, for 2–6 weeks as appropriate to the severity of dermatitis. A follow-up appointment is indicated if the condition has not resolved.
  • In acute vesicular dermatitis relief can often be obtained with moist compresses (10–20 minutes twice or thrice daily).

Systemic treatment

  • In cases of severe and spreading allergic contact dermatitis a short course of systemic glucocorticoids Dynamed may be indicated, e.g. prednisolone 20–40 mg once daily for 1–2 weeks.
  • Antimicrobials are very rarely needed in allergic dermatitis, and they do not replace topical treatment. If the rash is clearly infected (picture (Hand dermatitis in a patient with atopy)), an antimicrobial may be indicated (cephalexin 500 mg three times daily for 7–10 days).

Evidence Summaries

Immediate contact dermatitis

  • Unlike allergic dermatitis (delayed allergy), this is based on an immediate, IgE-mediated allergy
  • Contact urticaria and protein contact dermatitis
  • Redness, pruritus and/or urticaria develop immediately (less than 30 minutes) at the site of the allergen contact. Allergens include natural rubber (latex), cat or dog (dander or hair), root and other vegetables.
  • Clearly more rare than allergic contact dermatitis, but in its chronic state its appearance may resemble that of allergic dermatitis.

Specialist consultation

  • Consult a dermatologist in particularly severe and extensive cases as well as chronic forms of the conditions
  • Patch testing and the verification of diagnosis
  • A suspicion of occupational allergic contact dermatitis or hand dermatitis

References

1. Brar KK. A review of contact dermatitis. Ann Allergy Asthma Immunol 2021;126(1):32–39.  [PMID:33091591]
2. Tam I, Yu J. Allergic Contact Dermatitis in Children: Recommendations for Patch Testing. Curr Allergy Asthma Rep 2020;20(9):41.  [PMID:32548648]
3. Chu C, Marks JG Jr, Flamm A. Occupational Contact Dermatitis: Common Occupational Allergens. Dermatol Clin 2020;38(3):339–349.  [PMID:32475512]
4. Johansen JD, Aalto-Korte K, Agner T et al. European Society of Contact Dermatitis guideline for diagnostic patch testing - recommendations on best practice. Contact Dermatitis 2015;73(4):195-221.  [PMID:26179009]
5. Fonacier L, Bernstein DI, Pacheco K et al. Contact dermatitis: a practice parameter-update 2015. J Allergy Clin Immunol Pract 2015;3(3 Suppl):S1-39.  [PMID:25965350]
6. Boonstra MB, Christoffers WA, Coenraads PJ et al. Patch test results of hand eczema patients: relation to clinical types. J Eur Acad Dermatol Venereol 2015;29(5):940-7.  [PMID:25220568]
7. Johnston GA, Exton LS, Mohd Mustapa MF ym. British Association of Dermatologists' guidelines for the management of contact dermatitis 2017. Br J Dermatol 2017;176(2):317-329.  [PMID:28244094]
8. Bepko J, Mansalis K. Common Occupational Disorders: Asthma, COPD, Dermatitis, and Musculoskeletal Disorders. Am Fam Physician 2016;93(12):1000-6.  [PMID:27304769]

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