Seborrheic Dermatitis

Overview

Seborrheic dermatitis is a common, chronic-relapsing skin condition that affects sebaceous gland-rich areas such as the scalp, face, and trunk. It is characterised by erythema and greasy scale, often worsened by stress or cold weather. Though the pathophysiology is not fully understood, Malassezia yeast and individual susceptibility are implicated. This page outlines the clinical features and treatment of seborrheic dermatitis, including its distinct infantile and adult forms.

Aetiology

• Partly hereditary
• Associated with Malassezia yeast overgrowth
  • Metabolites may trigger an inflammatory reaction

Risk Factors

• Oily skin
• Family history of dermatitis or psoriasis
• Immunosuppression (e.g. HIV, post-transplant)
• Parkinson’s disease
• Stress and sleep deprivation

Epidemiology

• Bimodal age of onset:
  • Infants: within the first 3 months of life
  • Adults: between 20–50 years
• More common in males

Pathophysiology

• Not fully understood
• Likely involves:
  • Sebum production
  • Malassezia colonisation
  • Individual immune response

Clinical Features

General Characteristics

• Chronic and relapsing course
• Often improves in summer and worsens in winter
• Predominantly affects sebaceous-rich regions:
  • Scalp, face, trunk

Skin Lesions

• Ill-defined, salmon-pink plaques with greasy scale
• May appear in:
  • Nasolabial folds
  • Eyebrows
  • Scalp
  • Retroauricular area
  • Axillae, groin, and upper trunk

Ocular Involvement

• Blepharitis (inflammation and scaling of eyelid margins)

Infantile Seborrheic Dermatitis

• Onset within the first 3 months of life
• Erythematous but non-itchy lesions
• Affects scalp (“cradle cap”), face, neck, axillae, and nappy area
• Lesions are well-defined and covered in greasy yellow scale

Adult Seborrheic Dermatitis

• Erythema and fine scale on face, especially:
  • Cheeks, nose, nasolabial folds
• Greasy dandruff and scalp itching
• Well-defined erythema in intertriginous areas:
  • Axillae, groin, scrotum, and perianal region

Management

• Topical keratolytics (e.g. salicylic acid) to reduce scaling
• Topical antifungals (e.g. ketoconazole) to reduce Malassezia
• Mild topical corticosteroids for inflammation control
• Isotretinoin in resistant or moderate–severe adult cases

Summary

Seborrheic dermatitis is a chronic, inflammatory skin condition affecting sebaceous-rich areas. It presents with greasy scale and erythema, and may affect both infants and adults. Management involves antifungals, keratolytics, and occasionally corticosteroids or isotretinoin in severe cases. Recognition of seborrheic dermatitis is essential in differentiating it from other chronic dermatoses. For a broader context, see our Skin & Dermatology Overview page.