The bigger picture

Seborrhoeic dermatitis is considered to be the precursor of dandruff, and is thought to be associated with – though not caused by – the presence of yeasts of the Malassezia family. There is no link with hygiene, and the condition is believed to be relatively common, although it is difficult to put a figure on it, as many people do not seek medical help. Men are more likely to be affected than women, as are the very young (under three months of age, when it is usually called ‘cradle cap’), the middle-aged, people with Parkinson’s disease and those who are immune-compromised. Prevalence appears higher in the winter months.

The main symptom is red, greasy areas of skin that appear to be flaking. It may be itchy, and can affect the eyelids (blepharitis). Conditions it may be confused with include psoriasis, eczema, scabies, irritant dermatitis, candidiasis (thrush), and pityriasis versicolour. Treatment involves use of antifungal agents.