The response of seborrhoeic dermatitis to ketoconazole

A randomized double‐blind placebo‐controlled cross‐over study was made of ketoconazole 200 mg daily in nineteen patients with seborrhoeic dermatitis. All had scalp lesions and sixteen had seborrhoeic dermatitis at other sites. Responses were measured by clinician and patients independently, using a linear analogue scale. Body and scalp lesions and itch regressed considerably and significantly with ketoconazole in all but five patients, three of whom subsequently responded to a higher dose. The patients studied with seborrhoeic dermatitis had been sent by their family doctors in answer to a request for patients with dandruff, and the clinical difference between the two was found to be only of degree. Three patients with dandruff without erythema were studied separately using the same study design: all three responded similarly to those with seborrhoeic eczema. It is concluded that Pityrosporum yeast infection is the immediate cause of seborrhoeic dermatitis and that dandruff is its mildest manifestation.