Synopsis
Recognise infant and adult seborrhoeic dermatitis across skin tones, distinguish common mimics, use antifungal and anti-inflammatory treatment by site, and plan relapse prevention.
- Adult seborrhoeic dermatitis affects scalp, eyebrows, nasolabial folds, ears and central chest with scale and erythema, lighter or darker change.
- Cradle cap is usually self-limited and gently managed; an unwell infant, widespread eruption or growth failure needs paediatric assessment.
- Ketoconazole shampoo reduces scalp Malassezia: use twice weekly for two to four weeks, leave three to five minutes, then once every one to two weeks for prevention.
Key red flags
Erythroderma, fever, failure to thrive, severe eye involvement, extensive disease with immunosuppression, neurological decline or treatment-resistant atypical plaques warrants broader assessment.
Tender boggy scalp swelling, pustules, lymphadenopathy or hair loss suggests inflammatory tinea and risks permanent scarring.
Investigation priorities
Confirm a sebaceous-zone pattern and look for hair-shaft or nail clues to alternatives.
Management branches
Dandruff or seborrhoeic scalp inflammation occurs without alopecia, kerion or systemic illness.
- Use ketoconazole 2% shampoo twice weekly for two to four weeks, massaging into wet scalp and leaving for three to five minutes before rinsing.
- Add a short site-appropriate anti-inflammatory scalp preparation when itch and inflammation remain prominent after scale control.
Key medicines
Ketoconazole 2% shampooAdults and adolescents wet hair and scalp, lather, leave for three to five minutes and rinse; use twice weekly for two to four weeks, then once every one to two weeks.
Ketoconazole 2% creamAdults apply to affected and immediately surrounding skin once or twice daily for two to four weeks; intermittent once-weekly maintenance may then be used.