Contact Dermatitis

Acute contact (exogenous) dermatitis can be either irritant or allergic.

Features:

• itchy, inflamed skin

• red and swollen

• papulovesicular (esp. allergic)

• may be dry and allergic (esp. irritant)

Causes Irritant contact dermatitis: caused by primary irritants (e.g. acids, alkalis, detergents, soaps).

Allergic contact dermatitis (~80%): caused by allergens that provoke an allergic reaction in some individuals only, most people can handle the chemicals without undue effect. This allergic group also includes photocontact allergens. 4.5% of population is allergic to nickel and 1–3% to an ingredient in cosmetics.

Common allergens

• Ingredients (fragrances) in cosmetics (e.g. perfumes, preservatives)

• Topical antibiotics (e.g. neomycin)

• Topical anaesthetics (e.g. benzocaine)

• Topical antihistamines

• Plants (skin of mango cross-reacts with these): rhus, grevillea, primula, poison ivy

• Metal salts (e.g. nickel sulphate, chromate)

• Dyes, esp. clothing dyes

• Hairdressing chemicals

• Glutaraldehyde (e.g. sterilising agent)

• Rubber/latex

• Resins

• Toluene sulfonamide compound resin (e.g. nail polish)

• Coral

Management

• Determine cause with vigour and remove it. Patch testing helps confirm diagnosis. Consider usage test.

• Wash with water (only) and pat dry (avoid soap).

• Oral prednisolone for severe allergic cases: 25–50 mg/d for 1–2 wks, then reduce gradually over 1–2 wks.

• Topical corticosteroid cream (moderate to potent, depending on site)

• For chronic phase use fragrance-free moisturisers regularly, e.g. glycerol 10% in sorbolene cream.