Upgrade criteria (any one promotes the severity by one tier): psychosocial impact, eyebrow / eyelash loss, ≥ 6 months treatment non-response, rapid progression with positive hair-pull test.
What is Alopecia Areata?
Alopecia areata (AA) is an autoimmune disease — the immune system mistakenly attacks hair follicles, producing well-demarcated round/oval patches of hair loss. Onset is sudden; patients often discover it while shampooing or are told by their hairdresser.
| Alopecia areata | Androgenetic alopecia | Telogen effluvium | |
|---|---|---|---|
| Mechanism | Autoimmune | Androgens / genetics | Stress / postpartum / illness |
| Pattern | Sharply demarcated patches, smooth scalp | Receding hairline, vertex thinning | Diffuse global thinning |
| Onset | Sudden | Slow (years) | 2-3 mo after trigger |
| Hair pull test | Positive in active phase | Negative | Positive |
| Recovery | Mild self-resolves; severe needs treatment | No spontaneous recovery | 6-12 mo after trigger removal |
Taiwan TDA 2024 consensus: lifetime risk 1.7-2.1%; 66% onset before 30, 85.5% before 40. Pediatric/adolescent prevalence ~0.2-0.3%.
Why Does It Happen?
- Environmental triggers: infection (viral, bacterial), drugs, vaccines (rarely)
- Major psychological trauma or acute stress (bereavement, accident, surgery)
- Family history of AA or other autoimmune disease
- Coexisting autoimmunity: thyroid, vitiligo, atopic dermatitis, lupus
- Lifestyle (Taiwan studies): smokers 1.88× risk; obstructive sleep apnea bidirectional association
Note: stress is often overstated as the sole cause. ~50% of patients have a major stressor in the prior 6 months; the other 50% don't. AA is multifactorial.
Clinical Subtypes
- Patchy AA: most common; round/oval patches
- Ophiasis: band along temporal/occipital hairline; treatment-resistant
- Alopecia totalis: complete scalp hair loss (~30% of chronic cases progress)
- Alopecia universalis: complete body hair loss including eyebrows, eyelashes (~15% of chronic cases)
- Rapidly progressive AA: spreading to > 80% scalp within 3 months — emergency, needs steroid pulse
- Acute diffuse and total alopecia (ADTA): similar presentation but better prognosis (~80% recover within 6 months)
Diagnosis
Most cases diagnosed by clinical exam + trichoscopy:
- Exclamation-mark hairs — pathognomonic for active AA
- Black dots — broken hair shafts at scalp
- Sharply demarcated patches, smooth skin without erythema or scale
- Positive pull test (≥ 6 hairs released by gentle traction = active)
- Nail pitting — supportive evidence
Scalp biopsy needed only when distinguishing from tinea capitis, trichotillomania, primary scarring alopecia.
SALT Severity Assessment
- Mild: SALT ≤ 20%
- Moderate: SALT 20-50%
- Severe: SALT > 50%
TDA 2024 escalates severity by one grade if any of: psychological/social impact, eyebrow/eyelash involvement, ≥ 6 months of inadequate response, rapid progression with positive pull test.
Treatment Ladder (TDA 2024 + EU Consensus 2024)
Children < 12 years
| Severity | Recommended |
|---|---|
| All severities | Topical corticosteroid ± topical 5% Minoxidil |
| Severe (3-11 yo, off-label) | Systemic GC; tofacitinib 2.5-10 mg/d (off-label); MTX 0.3-0.6 mg/kg/wk |
Adolescents (12-18) and Adults
| Severity | 1st-line | 2nd-line |
|---|---|---|
| Mild-moderate (SALT ≤ 50%) | Potent topical CS or intralesional triamcinolone ± topical Minoxidil 5% | ± topical DPCP immunotherapy ± UV / excimer laser |
| Severe (SALT > 50%) | Oral / IV CS pulse ororal JAK inhibitor (Baricitinib, Ritlecitinib) | Oral MTX or Cyclosporine + UV / excimer ± topical DPCP |
JAK Inhibitor Era (key 2024 update)
| Baricitinib (Olumiant) | Ritlecitinib (Litfulo) | |
|---|---|---|
| Indication | Adults ≥ 18, severe AA (SALT > 50%) | ≥ 12 yo severe AA |
| Mechanism | JAK1 / JAK2 | JAK3 / TEC |
| Dose | 4 mg/d (2 mg if ≥75 yo or infection-prone) | 200 mg/d × 4 wk loading → 50 mg/d maintenance |
| Phase-3 efficacy | BRAVE-AA1/2 (n=1200): 36-wk SALT ≤ 20: 4 mg = 38.8% / 2 mg = 22.8% / placebo = 6.2% | ALLEGRO 2b/3 (n=718): 24-wk SALT ≤ 20: 31% (200/50) / 23% (50) / 2% placebo |
| Pre-treatment screening | TB (IGRA + CXR), HBV/HCV, HIV, CBC, lipids, LFT | TB, hepatitis, platelets, lymphocytes |
| Common AEs | URI, headache, acne, CK rise, HSV reactivation | Headache, folliculitis, acne, diarrhea |
EU 2024 Core Treatment Principles
- "Wait-and-see" is NOT advisable for severe AA — natural recovery only 0-16.7%; earlier treatment responds better
- Treatment goal: SALT ≤ 10 or SALT improvement ≥ 90% (replaces older SALT 20)
- Adjustment trigger: change/dose-modify if no goal achievement at 24-36 weeks
- Long-term maintenance: continue 6-12 months after complete regrowth; often required 3-7 years or even lifelong
- Re-treatment after relapse: ritlecitinib 2nd course only 57% respond — avoid premature discontinuation
- Combination: JAK + oral CS may enhance effect (small studies support)
- Adjuvant: low-dose oral minoxidil consider (not monotherapy); biotin not recommended unless deficiency confirmed
Comorbidities (Taiwan NHIRD studies)
- Anxiety, depression — elevated; some psychiatric disorders precede AA
- Stroke risk: 1.61× elevated
- Sensorineural hearing loss — cochlear melanocyte involvement
- Sleep apnea — 3.89× AA risk; bidirectional
- Other autoimmune: thyroid, atopic dermatitis, vitiligo, lupus, allergic rhinitis
- Cancer: overall slightly reduced (SIR 0.89, only male significant); but lymphoma, breast (especially < 50 yo women), kidney, bladder cancers elevated — periodic screening recommended
Summary
AA is not a death sentence, but neither is it "wait until you're happier and it'll go away." TDA 2024 + EU Rudnicka 2024 + BAD 2025 living guideline (Nov 2025, second iteration) give a clear pathway: mild = intralesional CS + topical; severe = oral JAK inhibitor (now ↑↑ strong recommendation for adults AND adolescents ≥ 12 per BAD 2025 R40 / R41), with oral CS often used as a bridge. Reassess at 36 weeks; some patients may need up to 18 months before declaring failure (R42/R44). Long-term treatment is usually required; abrupt cessation increases relapse risk (R45). Counsel on MHRA/FDA black-box warnings: VTE, MACE, cancer, death — caution if > 65 or with risk factors (R47). Long-term safety in adolescents is still unknown — registry enrollment encouraged (R48). JAK inhibitors are the biggest treatment breakthrough in 5 years, but not a cure-all. If a patch persists > 1 month, spreads rapidly, or affects eyebrows/eyelashes — see a dermatologist promptly.