Contact Dermatitis

Pathogenesis of Dermatitis Irritants Allergens type 1&4 Infection Endogenous factors

Contact Dermatitis Acute -redness, itching, vesiculation Chronic - scaly desquamation Site and morphology determined by causative exposure Irritant - caustic agents or detergents -hands ‘Allergic’ - rash 6-12 hours peaking at 48-72 hours

Irritant contact dermatitis Skin damaged directly by the irritant soaps, detergents, water, solvents, dry atmosphere etc very, very common at least 5% of the population suffer from hand dermatitis Treat with emollients/moisturisers

Delayed “allergy” Takes the immune system a few hours to react Allergic contact dermatitis (ACD) Common causes: nickel fragrances rubber additives preservatives plants medicaments etc

Sensitizers Nickel - wear >18 carat gold Rubber accelerators in elastic, gloves, shoes Permanent hair dyes -paraphenylenediamine Fragrances eg Balsam of Peru and cinnamic aldehyde present in cosmetics, soaps, perfumes and toothpastes - use ‘fragrance free’ products not just unscented. Adhesives and Varnishes Latex, Formaldehyde and Chromates Benzocaine and neomycin in topical medications

ACD Nickel allergy involves ears, skin under buckles and often the hands; accidental spread from the hands can affect the face Hair products - dyes and sprays - affect the face, neck and ears. Dyes in socks and shoes affect the feet. Medications for the treatment of leg ulcers can cause dermatitis of the legs