What is the first‑line management for a patient with classic seborrheic dermatitis presenting with scaly erythematous patches on the scalp, eyebrows, nasolabial folds, chest, or ears?

First-Line Management of Seborrheic Dermatitis

Apply ketoconazole 2% cream once daily to affected facial and body areas (nasolabial folds, eyebrows, chest, ears) for 2-4 weeks until clinical clearing, and use ketoconazole 2% shampoo or selenium sulfide 1% shampoo on the scalp, leaving it on for 3-5 minutes before rinsing. 1, 2, 3

Core Treatment Algorithm

For Scalp Involvement

• Apply 5 mL of antifungal shampoo (ketoconazole 2% or selenium sulfide 1%) directly to the scalp skin, ensuring contact with the scalp surface rather than just the hair shafts 1
• Leave the shampoo on for 3-5 minutes before rinsing to allow adequate contact time 1
• Initially use twice weekly for 2 weeks, then reduce frequency to weekly or every 2-4 weeks for maintenance 3
• Continue antifungal shampoo once weekly as prophylactic maintenance to prevent relapse, which significantly reduces recurrence rates compared to reactive treatment only 1

For Facial and Body Areas

• Apply ketoconazole 2% cream once daily to affected areas (nasolabial folds, eyebrows, chest, ears) for 2-4 weeks until clinical clearing 1, 2
• This addresses both the Malassezia yeast colonization and secondary inflammation that characterize seborrheic dermatitis 1, 4

Adjunctive Anti-Inflammatory Therapy for Active Flares

• For significant erythema and inflammation, add hydrocortisone 1% cream (low-potency corticosteroid) applied once or twice daily for short periods only—days to maximum 1-2 weeks 1, 5
• Never use medium- or high-potency steroids (triamcinolone, clobetasol, mometasone) on facial skin due to unacceptable risks of atrophy and telangiectasia 5
• Limit all corticosteroid use on the face to 2-4 weeks maximum to avoid skin atrophy, telangiectasia, and tachyphylaxis 5, 1

Essential Supportive Skin Care Measures

Cleansing Practices

• Use mild, pH-neutral (pH 5) non-soap cleansers or dispersible creams as soap substitutes to preserve the skin's natural lipid barrier 5
• Avoid regular soaps and detergents, as these strip natural skin lipids and worsen the condition 1, 5
• Use tepid water instead of hot water for cleansing 5

Moisturization Strategy

• Apply fragrance-free, non-greasy moisturizers containing humectants (urea ≈10% or glycerin) immediately after bathing to damp skin to restore barrier function and reduce dryness 5
• This creates a surface lipid film that prevents transepidermal water loss 5
• Pat skin dry with clean towels rather than rubbing 5

Products to Avoid

• Avoid all alcohol-containing preparations on the face, as they significantly worsen dryness and trigger flares 5, 1
• Avoid products containing neomycin, bacitracin, or fragrances due to high sensitization rates (13-30% with neomycin) 5
• Avoid perfumes, deodorants, and harsh soaps that disrupt the skin barrier 5
• Avoid greasy or occlusive products that can promote folliculitis 5

Management of Pruritus

• For moderate to severe itching, add oral antihistamines (cetirizina, loratadina, fexofenadina) 5
• Topical polidocanol-containing lotions can provide additional symptomatic relief 5
• Non-sedating antihistamines have little value in seborrheic dermatitis management 5

Critical Pitfalls to Avoid

Application Technique Errors

• Ensure shampoos reach the scalp skin rather than remaining only on hair shafts—this is a common reason for treatment failure 1
• Apply treatment no more than twice daily for scalp involvement to avoid irritation 5

Corticosteroid Misuse

• Avoid undertreatment due to "steroid phobia," but also avoid prolonged use beyond 2-4 weeks on the face 5, 1
• Never use potent corticosteroids on the face due to high risk of atrophy and telangiectasia 1

Monitoring for Complications

• Watch for secondary bacterial infection (increased crusting, weeping, pustules) suggesting Staphylococcus aureus, which requires oral flucloxacillin 5
• Look for grouped vesicles or punched-out erosions suggesting herpes simplex superinfection, which requires immediate oral acyclovir 5

When to Refer to Dermatology

• Diagnostic uncertainty or atypical presentation 5
• Failure to respond after 4 weeks of appropriate first-line therapy 5, 1
• Recurrent severe flares despite optimal maintenance therapy 5
• Need for second-line treatments (topical calcineurin inhibitors, systemic therapies) 5

Special Considerations by Skin Type

• In darker-skinned individuals, seborrheic dermatitis may present with hypopigmented macules and patches, arcuate or petal-like patches (petaloid seborrheic dermatitis), rather than classic erythema 6
• Treatment approach may need modification based on hair texture and washing frequency in patients of color 6