What is seborrhoeic dermatitis and how is it treated?

Seborrheic Dermatitis: Overview and Management

What is Seborrheic Dermatitis?

Seborrheic dermatitis is a chronic inflammatory skin condition characterized by greasy, flaky patches with erythema affecting sebum-rich areas including the scalp, face, eyebrows, ears, chest, and groin, often accompanied by pruritus. 1, 2

Pathophysiology

• The condition results from three key pathogenic factors: lipid secretion by sebaceous glands, colonization with Malassezia yeast species (which metabolize sebum triglycerides into irritating free fatty acids), and immunologic dysregulation that triggers inflammation 1, 2
• Malassezia species are believed central to pathogenesis, with therapeutic efficacy of antifungal agents providing strong supporting evidence 3, 4

Clinical Presentation Variations

• Classic presentation includes flaky, "greasy" patches and thin plaques with erythema, though appearance varies significantly by skin type 2
• In darker skin tones, hyper- or hypopigmentation may occur with minimal erythema and less obvious scaling, leading to potential misdiagnosis 2
• Scalp involvement may be mistaken for simple dandruff 1

Associated Medical Conditions

• Seborrheic dermatitis is significantly more pronounced in patients with HIV infection, Parkinson's disease, and Down syndrome 1
• Frequently coexists with ocular manifestations: 95% of patients with seborrheic blepharitis also have seborrheic dermatitis of the skin 1
• Co-occurs with dry eye conditions in 25-40% of cases 5, 1

Treatment Approach

First-Line Therapy

The most effective treatment combines topical antifungal medications (to reduce Malassezia yeast) with topical anti-inflammatory agents (to control inflammation and itching). 6

Topical Antifungal Treatment

• Ketoconazole 2% is the first-line antifungal agent with an 88% response rate after initial treatment 6, 7
• For scalp involvement: Apply ketoconazole 2% shampoo, leaving on scalp for 3-5 minutes before rinsing 6, 7
• For facial/body involvement: Apply ketoconazole 2% cream twice daily for four weeks or until clinical clearing 3
• Alternative antifungals include selenium sulfide 1% shampoo and ciclopirox 6, 4

Anti-Inflammatory Treatment

• Low-potency topical corticosteroids (hydrocortisone 1% or prednicarbate 0.02%) should be used for significant erythema and inflammation, limited to 2-4 weeks maximum, especially on the face 6
• For scalp with significant inflammation: Adding clobetasol propionate 0.05% shampoo twice weekly provides superior efficacy compared to ketoconazole alone 6
• Avoid long-term corticosteroid use on the face due to high risk of skin atrophy, telangiectasia, tachyphylaxis, and acneiform eruptions 6

Formulation Selection by Location

• For scalp: Use shampoos, gels, solutions, or foams rather than ointments or creams, as hair makes traditional formulations messy and difficult to apply 6
• For face: Avoid alcohol-containing preparations as they significantly worsen dryness and trigger flares 1, 6

Supportive Skin Care Measures

• Use mild, pH-neutral (pH 5) non-soap cleansers or dispersible creams as soap substitutes to preserve the skin's natural lipid barrier 6
• Apply fragrance-free emollients containing petrolatum or mineral oil immediately after bathing to damp skin to create a surface lipid film that prevents water loss 1, 6
• Use tepid (not hot) water for bathing, as hot water worsens symptoms 6
• Pat skin dry with clean towels rather than rubbing 6

Maintenance Therapy

• Due to the chronic, relapsing nature of seborrheic dermatitis, maintenance therapy with emollients and intermittent anti-inflammatory treatment is necessary 1
• Consider switching to ketoconazole shampoo for long-term maintenance if scalp is affected 6
• Reapply moisturizer every 3-4 hours and after each face washing 6

Alternative and Adjunctive Therapies

• Coal tar preparations (1% strength preferred) can reduce inflammation and scaling in scalp seborrheic dermatitis 5, 6
• Narrowband UVB phototherapy has shown efficacy in open studies for recalcitrant cases not responding to topical therapy 6
• Oral antihistamines (cetirizine, loratadina, fexofenadina) may help reduce pruritus and minimize scratching-related damage 1, 6
• Avoid non-sedating antihistamines as they provide no benefit in seborrheic dermatitis 6

Emerging Therapies

• Topical phosphodiesterase-4 inhibitors (roflumilast 0.3% foam) show promise as effective, non-corticosteroid options 2, 8

Critical Pitfalls to Avoid

• Never use greasy or occlusive products as they can promote folliculitis development 6
• Avoid harsh soaps and detergents that remove natural lipids from skin surface 6
• Do not apply topical acne medications (especially retinoids) as their drying effects worsen the condition 6
• Avoid perfumes, deodorants, and alcohol-based lotions that trigger flares 6
• Do not undertreat due to fear of corticosteroid side effects—use appropriate potency for adequate duration, then taper 6
• Keep nails short to minimize trauma from scratching 6

Monitoring for Complications

• Watch for secondary bacterial infection (crusting, weeping) requiring oral flucloxacillin for Staphylococcus aureus 6
• Suspect herpes simplex superinfection if grouped vesicles or punched-out erosions appear—initiate oral acyclovir immediately 6

When to Refer to Dermatology

Refer to dermatology if: 6

• Diagnostic uncertainty or atypical presentation exists
• Failure to respond after 4-6 weeks of appropriate first-line therapy
• Recurrent severe flares despite optimal maintenance therapy
• Need for second-line treatments or systemic therapy
• Suspected alternative diagnoses (psoriasis, atopic dermatitis, contact dermatitis, cutaneous T-cell lymphoma)

Differential Diagnosis Considerations

• Psoriasis: Look for well-demarcated, indurated plaques with thick silvery scale (not greasy yellow scales), with sharper definition than seborrheic dermatitis 6
• Atopic dermatitis: More intense pruritus, lichenification in chronic cases, flexural involvement more common 6
• Contact dermatitis: Sharp demarcation corresponding to contact area 6
• Cutaneous T-cell lymphoma: Consider if refractory to standard treatment 6