Seborrhoeic dermatitis in adults is a chronic dermatitis thought to be caused by an inflammatory reaction related to a proliferation of a normal skin inhabitant, a fungus called Malassezia furfur It is common, affecting around 2% of the general population.

Associated conditions include

• HIV
• Parkinson's disease

Features

• eczematous lesions on the sebum-rich areas: scalp (may cause dandruff), periorbital, auricular and nasolabial folds
• otitis externa and blepharitis may develop

Management

Scalp disease management

• over the counter preparations containing zinc pyrithione ('Head & Shoulders') and tar ('Neutrogena T/Gel') are first-line
• the preferred second-line agent is ketoconazole
• selenium sulphide and topical corticosteroid may also be useful

Face and body management

• topical antifungals: e.g. ketoconazole
• topical steroids: best used for short periods