Alopecia Areata - Treatment

Pathophysiology (Why the Treatments Work)

JAK inhibitors suppress CD8+ T-cell activity and also directly promote hair growth. - Fitzpatrick's Dermatology, Fig. 13-4

Treatment by Disease Extent

1. Localized / Patchy AA (< 50% scalp involvement)

• Triamcinolone acetonide 2.5-10 mg/mL, injected intradermally or in superficial subcutaneous tissue
• Higher concentrations and larger volumes carry greater risk of local atrophy
• Injection under high pressure (small-bore syringe) risks retinal artery embolization

• Squaric acid dibutylester (SADBE), diphencyprone (DPCP), dinitrochlorobenzene (DNCB)
• Induces a low-grade allergic contact dermatitis that "distracts" the immune attack on follicles

2. Moderate-to-Severe / Rapidly Progressing AA

FDA-Approved JAK Inhibitors (the major advance of the 2020s)

• Baricitinib has the longest safety track record (prior RA/atopic dermatitis approvals)
• Ritlecitinib's JAK3/TEC profile may cause less dyslipidemia than JAK1/2 agents; the only approved option for adolescents
• Deuruxolitinib requires CYP2C19 genotyping before initiation (metabolized by CYP2C19)

Off-label oral/topical JAK inhibitors

• Tofacitinib (JAK1/3) - ~58% achieving ≥50% SALT response off-label
• Ruxolitinib (JAK1/2) - topical formulation showing promise in off-label use (2025 systematic review, PMID 40192197)

3. Alopecia Totalis / Universalis / Ophiasis

• 60% of widespread patchy AA responds; ~50% of totalis, ~25% of universalis

• Ophiasic pattern does NOT respond
• Predictors of response: disease duration ≤ 6 months, onset < 10 years, multifocal pattern

Treatment Algorithm Summary

Localized AA (patches)
  └─ Intralesional triamcinolone ± topical steroids ± minoxidil

Moderate-severe / rapidly progressing
  └─ Oral JAK inhibitor (baricitinib, ritlecitinib, or deuruxolitinib)
       ├─ Consider disease duration, comorbidities, age (ritlecitinib ≥12 yr)
       └─ Monitor for boxed-warning adverse effects

Refractory / extensive (totalis, universalis)
  └─ JAK inhibitor (first choice based on current evidence)
  └─ Contact immunotherapy (DPCP/SADBE) if JAK inhibitor unavailable/contraindicated
  └─ Pulsed systemic corticosteroids, PUVA, cyclosporine as alternatives

What Does NOT Work Well

• Biologics (TNF inhibitors, IL-17/23 inhibitors): largely disappointing results; AA has paradoxically developed during biologic therapy for other diseases
• Spontaneous remission is common in mild patchy disease (most recover within 1-2 years without treatment), so anecdotal "treatment successes" must be interpreted cautiously

Emerging / Investigational

• Additional JAK inhibitors and selective TYK2 inhibitors in trials
• IL-2 pathway modulators (based on GWAS findings at IL2/IL21 loci)
• 308-nm excimer laser: some reports of regrowth after ~11-12 sessions; evidence limited

Key Recent Evidence

• Cochrane network meta-analysis (PMID 37870096, Oct 2023): JAK inhibitors superior to conventional therapies for moderate-severe AA
• JAK inhibitor systematic review/meta-analysis (PMID 37368402, JAMA Network Open 2023): confirmed efficacy of JAK inhibitors across AA subtypes
• Ritlecitinib vs baricitinib indirect comparison (PMID 39445776, JEADV 2025): both agents effective; cross-trial comparisons suggest broadly similar SALT response rates
• Network meta-analysis of monotherapies (PMID 40231941, 2025): JAK inhibitors rank highest among current options
• Long-term data (EADV 2025): baricitinib shows sustained efficacy to 5 years; ritlecitinib shows 61% SALT ≤20 at 2 years with 84% sustainability among initial responders at 3 years