Contact Dermatitis

Definition

• Inflammation of the skin due to exposure to an irritant or allergen

• Two main types:

  • Allergic contact dermatitis (ACD): Type IV delayed hypersensitivity

  • Irritant contact dermatitis (ICD): Direct skin damage from irritants

Aetiology & Causes

• ACD: Can develop even if previously tolerated; triggered by small amounts of allergen.

• ICD: More common, especially in those with atopic eczema.

Symptoms

Diagnosis

• Usage Test: Apply suspected allergen to cubital fossa morning and night for up to 7 days

• Patch Testing if cause remains unclear

Management

• General Measures

  • Identify and avoid triggers

  • Use soap-free washes and emollients to protect the skin

• Pharmacological Treatment

  • Topical steroids (e.g. betamethasone dipropionate 0.05% once daily until clear, max 4 weeks)

  • Oral corticosteroids (e.g. prednisolone 25–50 mg for 1 week, then taper over 2 weeks) for severe or extensive disease

  • Oral antihistamines (e.g. cetirizine, loratadine) may help relieve itch

Notes

• Irritant dermatitis: More common, typically involves hands; presents with burning sensation and dryness/cracking rather than vesicles.

• Allergic dermatitis: Often has well-demarcated lesions with vesicles/bullae and intense itching.

• Avoid triggers, use soap-free products, and maintain good skin hydration with emollients.

• Topical steroids are first-line therapy; oral steroids may be necessary for severe or widespread cases (taper to prevent rebound).