What is the recommended treatment approach for scalp psoriasis, including first‑line topical options, second‑line phototherapy, and systemic or biologic therapies?

Scalp Psoriasis Treatment

First-Line Treatment: Topical Corticosteroids with Vitamin D Analogues

For scalp psoriasis, initiate treatment with the fixed-combination product calcipotriene 0.005% plus betamethasone dipropionate 0.064% gel or foam applied once daily, which achieves 69-74% of patients reaching clear or almost clear status within 52 weeks. 1

Why This Combination Works Best

• The combination of calcipotriene with potent corticosteroids is more effective than either agent alone, with 69-74% achieving clear/almost clear status versus only 27% with vehicle. 1, 2
• Corticosteroids provide rapid improvement within 2-4 weeks, addressing the inflammation component, while vitamin D analogues sustain long-term control by inhibiting keratinocyte proliferation. 1, 2
• Once-daily application with the fixed-combination product improves adherence compared to separate applications of each agent. 2
• No serious adverse events, including striae or hypothalamic-pituitary-adrenal axis suppression, were observed over 52 weeks of continuous use. 1

Vehicle Selection Matters

• Use solutions, foams, gels, or shampoos rather than creams or ointments for the scalp, as these vehicles improve adherence and efficacy. 1
• For African American patients, oil-based preparations are often preferred for compatibility with routine hair care. 1

Treatment Algorithm by Severity

Mild to Moderate Scalp Psoriasis

• Start with class 3-7 topical corticosteroids (medium to low potency) combined with calcipotriene. 1
• Apply once daily for a minimum of 4 weeks, with treatment duration up to 8 weeks for optimal vitamin D analogue effect. 1

Moderate to Severe Scalp Psoriasis

• Use class 1-2 high-potency corticosteroids (e.g., betamethasone dipropionate) combined with calcipotriene. 1
• After initial control, gradually reduce corticosteroid frequency to prevent rebound while continuing vitamin D analogue. 1

Critical Timing Considerations

• Vitamin D analogues show efficacy at 8 weeks but not at 4 weeks—counsel patients about this timeline to maintain adherence. 1
• Corticosteroids achieve maximal efficacy within 3-4 weeks, making them essential for rapid symptom control. 3, 4

Important Safety Caveats

• Do not combine calcipotriene with salicylic acid, as the acidic pH inactivates the vitamin D analogue. 5
• Apply calcipotriene after phototherapy, not before, since UVA radiation decreases its skin concentration. 1, 5
• Limit total weekly vitamin D analogue use to ≤100g to prevent hypercalcemia. 5
• For women of childbearing potential, most topical psoriasis medications are pregnancy category C; tazarotene is category X. 1

When Topical Therapy Fails: Escalation to Systemic Treatment

Scalp psoriasis qualifies as a "vulnerable area" that warrants systemic therapy when topical treatment fails, particularly with symptomatic disease or more than minimal impact on quality of life. 6, 1

Biologic Therapy for Severe Cases

• Infliximab is recommended as monotherapy for moderate-to-severe scalp psoriasis (Strength of Recommendation B), administered as 5 mg/kg infusions at weeks 0,2, and 6, then every 8 weeks. 6
• Etanercept is supported by Level I-III evidence for scalp psoriasis, starting at 50 mg twice weekly for 12 weeks, then 50 mg weekly maintenance. 6
• Consider biologics (anti-IL-17, anti-IL-23, or TNF inhibitors) for severe cases that have failed topical therapy and phototherapy. 1, 7
• TNF-alpha inhibitors are contraindicated in patients with demyelinating diseases like multiple sclerosis. 1

Phototherapy Options

• Narrowband UVB phototherapy is a well-tolerated, cost-effective systemic option for widespread or refractory scalp psoriasis. 1
• PUVA photochemotherapy is more efficacious than NB-UVB for thick lesions and darker skin due to better UVA penetration. 1

Conventional Systemic Agents

• Methotrexate is effective for severe, recalcitrant, disabling scalp psoriasis not responsive to other therapies, but is contraindicated with significant alcohol intake or liver disease. 1
• Acitretin can be used as monotherapy or combined with NB-UVB, particularly suitable for postmenopausal women, but is teratogenic and contraindicated in women of childbearing potential. 1

Long-Term Management Strategy

• After achieving control, use weekend-only corticosteroid application while continuing calcipotriene five days per week to maintain efficacy while reducing steroid exposure. 5
• Twice-weekly maintenance therapy in frequent relapsers may decrease time to first relapse. 7
• For localized non-responding or very thick lesions, use intralesional triamcinolone acetonide up to 20 mg/mL every 3-4 weeks. 1

Common Pitfalls to Avoid

• Poor adherence is common due to inconvenience and messy formulations—selecting the right vehicle is critical. 1
• Do not assume treatment failure at 4 weeks with vitamin D analogues; reassess at 8 weeks. 1
• Avoid prolonged high-potency corticosteroid monotherapy beyond 4 weeks without physician supervision to prevent skin atrophy and systemic absorption. 1
• If apparent treatment failure occurs, first assess adherence rather than assuming tachyphylaxis, as true receptor down-regulation is rare. 5