Alopecia Areata: JAK Inhibitors
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Direct answer
Two oral JAK inhibitors — baricitinib 2-4 mg daily and ritlecitinib 50 mg daily — are the first approved systemic drugs for severe alopecia areata, interrupting the interferon-gamma and IL-15 signalling that drives cytotoxic T-cell attack on the follicle. Entry criteria in trials meant a SALT score of 50 or more, meaning at least half the scalp hair lost, the population where topical and intralesional options flounder. Treatment is preceded by tuberculosis, hepatitis and zoster screening plus baseline blood counts, lipids and liver tests, because the class carries boxed warnings for serious infections, thromboembolism, major cardiac events and malignancy. Regrowth is slow: judge at 3-6 months, accept best results at a year, and warn that relapse follows drug withdrawal.
What you must remember
- Approved agents and doses: baricitinib 4 mg daily (2 mg in special situations), ritlecitinib 50 mg once daily, and more recently deuruxolitinib 8 mg twice daily in several jurisdictions — baricitinib and ritlecitinib anchor exam answers.
- Age point: ritlecitinib carries approval down to 12 years of age — the first systemic option for adolescents with extensive disease.
- Severity metric: the SALT score quantifies scalp hair loss from 0 to 100; SALT 50 was the trial entry threshold, and a treatment target of SALT 20 or less represents meaningful regrowth.
- Pretreatment screen: latent tuberculosis (Mantoux or IGRA with chest radiograph), hepatitis B and C, HIV, zoster status, complete blood count, lipid profile and liver enzymes.
- Boxed-warning logic: the class warnings flow from post-marketing rheumatoid arthritis data with tofacitinib (the ORAL Surveillance programme), not from dermatology trials — quote it accurately in vivas.
- Commonest adverse events: herpes zoster reactivation, nasopharyngitis, headache, and lipid elevations; acne and folliculitis appear in younger patients.
- Do not combine: JAK inhibitors are not stacked with each other, with biologics or with broad immunosuppressants.
- The Indian workhorses: intralesional triamcinolone 2.5-5 mg/mL for patchy disease and diphenylcyclopropenone contact immunotherapy for extensive involvement remain staples; systemic steroids rescue rapid-onset widespread loss but never as maintenance.
A worked treatment sequence for extensive disease
Consider a 19-year-old girl with 70 per cent scalp loss plus eyebrow thinning over eight months, Ferritin and thyroid profile normal, no atopy or autoimmune thyroid disease. Counselling comes first: prognosis correlates inversely with extent, onset in childhood, atopy and nail pitting — she accumulates one bad factor, extent alone. Because her disease is advancing quickly, a short tapering course of oral prednisolone 0.5 mg/kg checks the avalanche while the plan is assembled. For sustained therapy she chooses baricitinib 4 mg daily after negative tuberculosis and hepatitis screens; zoster counselling includes reporting any dermatomal pain immediately. At month 3, vellus regrowth appears at the occiput; at month 6 her SALT has fallen to 28; at month 12 she sits at SALT 15 with eyebrows recovered. The conversation now covers drug holidays, the risk of relapse within months of stopping, and the fallback of DPCP immunotherapy — cheaper, clinic-administered, with its own irritant and pigmentary issues in Indian skin — if cost forces a switch.
Where the examiner probes
Single-best-answer papers like pairing the molecule with the pathway: baricitinib inhibits JAK1 and JAK2, ritlecitinib JAK3 and TEC-family kinases — the common thread is blockade of signal transduction downstream of the interferon-gamma receptor on the follicular epithelium. Viva examiners probe the ethics of the boxed warning: be ready to justify why a young woman with disfiguring but non-fatal disease accepts thrombosis and infection risk, and how you document shared decision-making. The third favourite angle is the differential of a SALT-70 presentation — patchy loss with exclamation-mark hairs and nail pitting confirms alopecia areata, while scarring, patterned or diffuse shedding (lichen planopilaris, androgenetic alopecia, telogen effluvium) demands trichoscopy or biopsy before any immunosuppression begins.
Frequently asked questions
What SALT score defines severe alopecia areata for systemic therapy?
SALT 50 or greater, indicating at least half of scalp hair lost, was the entry criterion for the pivotal baricitinib and ritlecitinib trials.
Which JAK inhibitor is approved for adolescents with alopecia areata?
Ritlecitinib 50 mg daily, approved down to 12 years of age in multiple jurisdictions.
What screening precedes JAK inhibitor initiation?
Tuberculosis, hepatitis B and C and HIV testing, plus baseline full blood count, lipids and liver enzymes, with zoster counselling.
Why do JAK inhibitors carry boxed warnings?
Class warnings for serious infections, venous thromboembolism, major adverse cardiac events and malignancy derive from tofacitinib rheumatoid arthritis safety studies and apply across the class.
What happens to regrown hair when the drug is stopped?
Relapse is the rule rather than the exception, usually within months, so withdrawal needs a planned fallback such as contact immunotherapy.