Selecting the Optimal JAK Inhibitor for Alopecia Areata

Alopecia areata (AA) is an autoimmune condition in which the immune system targets hair follicles, causing sudden patches of hair loss. In some patients, the disease progresses to complete scalp hair loss (alopecia totalis) or loss of all body hair (alopecia universalis). Beyond its physical signs, AA carries a significant psychosocial burden, including decreased self-esteem and higher rates of depression and anxiety.¹ Until recently, systemic options were limited and often ineffective. Since 2022, the US Food and Drug Administration (FDA) has approved three oral JAK inhibitors: baricitinib, ritlecitinib, and deuruxolitinib.  Each drug differs in selectivity, age indication, safety profile, and strength of clinical evidence, making it important to match the right option to the right patient.

Mechanisms in Brief

The JAK/STAT signaling pathway plays a central role in AA. Cytotoxic T cells attack the hair follicle by releasing inflammatory signals such as interferon-γ and interleukin-15. These signals converge on JAK proteins inside the cell, which activate downstream STAT proteins and perpetuate follicular inflammation. By blocking JAK activity, inhibitors disrupt this inflammatory cascade and allow hair regrowth.²

Baricitinib (JAK1/2 inhibitor)

Baricitinib was the first oral drug approved for AA in 2022. Its main advantage is well-documented efficacy from two large phase 3 clinical trials (BRAVE-AA1 and BRAVE-AA2). In these studies, approximately 35% to 43% of patients taking the higher 4-mg dose achieved a Severity of Alopecia Tool (SALT) score of ≤20 by 36 weeks.3 The SALT score is a standardized way to measure hair loss, where 0 means full scalp coverage and 100 means complete baldness. A score of ≤20 translates to at least 80% scalp hair regrowth, which is an outcome that patients notice as cosmetically meaningful. By contrast, only about 5% to 10% of patients receiving placebo achieved this level of regrowth, highlighting the treatment effect. Longer-term data extending out to 2 years have shown that many patients are able to sustain their regrowth on continued therapy.⁴

The main disadvantages of baricitinib come from its safety profile. Like other JAK1/2 inhibitors, it carries boxed warnings for infections, blood clots, and changes in laboratory parameters such as cholesterol and blood counts. However, in the BRAVE-AA trials, serious adverse events were uncommon (2.1% to 3.4%), with most adverse events mild to moderate.³ Although laboratory monitoring was required, most abnormalities were mild (Grade 1) and manageable with standard monitoring protocols.

Ritlecitinib (JAK3/TEC inhibitor)

Ritlecitinib, approved in 2023, stands out as the only oral systemic therapy currently available to adolescents as young as 12 years old. Its approval came from the ALLEGRO Phase 2b/3 trial, in which approximately 23% of patients achieved at least 80% scalp coverage after 6 months on treatment compared to less than 2% in the placebo group.⁵ While this percentage may seem lower than baricitinib’s trial results, it is important to recognize that trial populations differed, and a meaningful subset of patients on ritlecitinib experienced significant regrowth. Ritlecitinib works differently from baricitinib by targeting JAK3 and TEC kinases rather than JAK1/2. This difference may reduce the risk of some of the cardiovascular and thromboembolic adverse events associated with JAK1/2 inhibition, though head-to-head comparative data are lacking.

The most common side effects seen in trials were relatively mild, including headache, diarrhea, acne, and rash.⁴  These events typically did not require discontinuation. The main limitation is that long-term data on durability and safety are still limited compared with baricitinib. Practically, ritlecitinib is the most appropriate choice for pediatric and adolescent patients or for those in whom avoiding JAK1/2 safety risks is particularly important.

Deuruxolitinib (JAK1/2 inhibitor)

Deuruxolitinib, approved in 2024, shares its mechanism with baricitinib as a JAK1/2 inhibitor but represents a new option in this class. Phase 3 trials showed robust regrowth, with efficacy rates comparable to baricitinib.6 In practical terms, nearly half of patients taking deuruxolitinib achieved at least 80% scalp coverage after 6 to 12 months of treatment.

The disadvantages of deuruxolitinib are similar to baricitinib’s, including risk for infections, lab abnormalities, and potential cardiovascular complications. Like baricitinib, it requires baseline and ongoing monitoring of blood counts and metabolic parameters. Clinically, deuruxolitinib provides an additional JAK1/2 option for adults, which may be valuable when insurance restrictions or access barriers prevent use of baricitinib.

Upadacitinib (JAK1 inhibitor, off-label use)

Upadacitinib is not FDA-approved for AA but is increasingly used off-label, especially in patients with comorbid autoimmune conditions such as atopic dermatitis or inflammatory bowel disease. In the Phase 3 UP-AA trial, about 45% of patients taking 15 mg and 54% taking 30 mg achieved SALT ≤20 by 24 weeks, compared to just 3% of patients on placebo.7 In plain terms, roughly half of treated patients had regrown at least 80% of their scalp hair in 6 months, while very few patients without treatment achieved that outcome. A scoping review of 64 published cases also found that many patients achieved meaningful regrowth within 1 to 4 months, and in patients with comorbidities like atopic dermatitis, both diseases improved simultaneously.⁸

The disadvantages of upadacitinib include that it is not FDA-approved for AA, so insurance coverage is inconsistent, and safety in this population has not been fully studied long term. Nonetheless, its targeted JAK1 inhibition may make it appealing for patients with overlapping conditions, or in those who have not responded to FDA-approved agents.

Topical JAK Inhibitors

Topical JAK inhibitors are a reasonable consideration for localized AA, cosmetically sensitive areas (eg, eyebrows), or for patients and parents who wish to avoid systemic risk or are ineligible for oral therapy. The current evidence base consists largely of case reports and small studies with heterogeneous formulations and endpoints, and an evidence-based review concludes that data remain limited and mixed, with ongoing evaluation of agents such as delgocitinib in randomized settings.9 Overall, topical JAK therapy can be positioned as an adjunct or step-up/step-down option, particularly to target focal, visible sites, while acknowledging that scalp penetration may limit efficacy compared with oral JAK inhibitors.⁹

A frequently cited signal comes from a case of topical ruxolitinib 0.6% cream twice daily that produced near-complete eyebrow regrowth by 12 weeks and modest (approximately 10%) scalp regrowth, with good tolerability; a small, stable reduction in white blood cell count suggested some systemic absorption but no clinical sequelae.¹⁰ This supports a pragmatic role for topical JAKs when the cosmetic burden is highest in brows or lashes or when patients are reluctant to start systemic therapy.¹⁰

However, the literature on topical JAK inhibitors in AA remains very limited, with conflicting or statistically non-significant results in most controlled studies. Importantly, before 2022, when no FDA-approved systemic options for AA were available, topical JAKs were used primarily off-label. Contemporary reviews note conflicting outcomes in AA with topical ruxolitinib, and systematic evidence syntheses that catalog topical trials (eg, topical ruxolitinib and delgocitinib) show inconsistent efficacy signals, often failing to meet primary endpoints.^11,12 Recent reports also highlight treatment variability across the JAK inhibitor class. A 2025 case series published by Kalil and colleagues described successful regrowth with one JAK inhibitor after inadequate response to others, underscoring the heterogeneity of patient outcomes and the need for individualized therapeutic selection.¹³

Practical Scenarios

Adolescents and young adults (≥12 years old)

For patients in this age group, ritlecitinib is currently the only FDA-approved oral systemic option. This makes it the first-line systemic therapy when a teenager presents with severe, diffuse alopecia areata that has failed to respond to topical or intralesional corticosteroids. The approval down to age 12 is supported by the ALLEGRO Phase 2b/3 trial, in which approximately 23% of patients achieved ≥80% scalp coverage at 6 months compared with 1.6% in the placebo group.⁵ In addition, ritlecitinib’s JAK3/TEC selectivity may reduce risks linked to JAK1/2 inhibitors, an important consideration for younger patients with decades of treatment ahead of them.⁵

Adults seeking rapid regrowth for psychosocial or professional reasons

Some patients face high urgency for visible hair regrowth—eg, individuals preparing for major life events, public-facing careers, or those with severe psychosocial distress. In this scenario, baricitinib or deuruxolitinib may be preferred. In the BRAVE-AA1/AA2 trials, 35% to 43% of patients on baricitinib 4 mg achieved ≥80% scalp coverage by week 36, compared with 4% to 10% on placebo.³ Longer-term follow-up has confirmed sustained efficacy out to 104 weeks.⁴ Similarly, deuruxolitinib phase 3 studies demonstrated robust regrowth rates comparable to baricitinib, with nearly half of treated patients reaching ≥80% coverage by 6 to 12 months.6 These data highlight the practical use of JAK1/2 inhibitors for patients seeking fast, cosmetically meaningful regrowth.

Patients with comorbid autoimmune diseases

When a patient presents with alopecia areata alongside other immune-mediated conditions such as atopic dermatitis or Crohn’s disease, upadacitinib may be considered despite being off-label. In the UP-AA trial, 45% of patients taking 15 mg and 54% taking 30 mg achieved ≥80% scalp coverage by 24 weeks, compared to 3% of placebo patients.⁷ A scoping review of 64 published cases also found that many patients achieved regrowth within 1 to 4 months, with coexistent atopic dermatitis often improving in parallel.⁸ In these scenarios, upadacitinib offers the unique advantage of addressing multiple conditions simultaneously, which can simplify management and improve adherence.

Patients at higher risk of adverse events

In patients with cardiovascular risk factors, history of thrombosis, or other contraindications to JAK1/2 inhibitors, ritlecitinib may be a safer alternative. Its JAK3/TEC inhibition avoids some of the systemic immune pathways modulated by JAK1/2, theoretically lowering certain risks.⁵ While long-term comparative data are still evolving, this distinction supports ritlecitinib’s role in patients for whom safety concerns outweigh the need for rapid regrowth.

Patients with limited capacity for monitoring

All JAK inhibitors require laboratory monitoring, but the frequency and scope may influence treatment choice. Baricitinib and deuruxolitinib require more extensive monitoring due to their JAK1/2 inhibition and broader systemic immune effects.^3,6 In contrast, ritlecitinib has shown a relatively mild side effect profile, with adverse events such as headache, diarrhea, and acne being the most commonly reported.⁵ For patients with limited access to regular lab testing, ritlecitinib may represent the most feasible option.

Conclusion

The introduction of oral JAK inhibitors has transformed care for patients with AA, providing for the first time systemic options that consistently promote meaningful hair regrowth. Baricitinib and deuruxolitinib offer strong efficacy for adults, ritlecitinib expands treatment to adolescents, and upadacitinib (though off-label) has emerging data that make it a consideration in refractory cases or when comorbid autoimmune disease is present. By understanding the advantages, disadvantages, and clinical trial outcomes in clear terms, dermatologists can select the right therapy for each patient, aligning treatment goals with safety and practicality.