Two phase 3 trials of the JAK inhibitor upadacitinib produced substantial scalp hair regrowth in roughly half of patients with severe alopecia areata. Published in JAMA Dermatology, the results showed that 55 percent of patients on the higher dose in one trial and 54.3 percent in the other reached at least 80 percent scalp coverage at 24 weeks.
Those figures sit at the upper end of what has been reported for this class, but the comparison has to be made carefully. In their own pivotal trials, the approved oral JAK inhibitors reported response rates on the same measure ranging from roughly 23 percent to 39 percent, and those trials used different time points, different populations, and different comparators. None was run head-to-head against upadacitinib.
Upadacitinib is not approved for alopecia areata. A manufacturer application is under FDA review, and nothing about this publication changes what a dermatologist can prescribe today.
The Trial Design and Results
UP-AA1 and UP-AA2 were parallel replicate trials, meaning two independently randomized studies run under a single protocol so that each could confirm the other. Together, they enrolled 1,399 patients at 112 centers in 25 countries and 125 centers in 28 countries, respectively, running from October 2023 to July 2025.
Participants were adolescents aged 12 to 17 weighing at least 30 kilograms, or adults under 64, with a Severity of Alopecia Tool score of 50 or higher and no spontaneous scalp regrowth in the prior six months. The SALT score runs from 0, meaning no scalp hair loss, to 100, meaning complete loss. The mean baseline score across both trials was 83.9, describing a population with extensive hair loss.
Patients were randomized in a 2:2:1 ratio to once-daily upadacitinib at 15 mg, 30 mg, or placebo for 24 weeks, followed by a blinded extension.
The primary endpoint was a SALT score of 20 or less, which corresponds to at least 80 percent scalp coverage. In UP-AA1, 45.2 percent on the lower dose and 55 percent on the higher dose reached it, against 1.5 percent on placebo. In UP-AA2, the figures were 44.6 percent and 54.3 percent, compared with 3.4 percent. Separation from placebo appeared as early as week 8.
On the stricter measure of complete scalp regrowth, meaning a SALT score of zero, 20.3 percent of higher-dose patients in the first trial and 22.5 percent in the second achieved it, compared with 0 percent and 0.7 percent on placebo.
Eyebrow and eyelash regrowth improved significantly on both doses, and patients reported greater improvement on alopecia-specific quality-of-life measures.
Translating a Clinical Score into a Mirror
Clinical scores translate imperfectly into what a person sees in a mirror, and understanding the difference matters before anyone forms expectations.
A SALT score of 20 means roughly 80 percent scalp coverage. That is a substantial visible change for someone starting with almost no hair, but it is not a full head of hair, and patchiness can remain. A score of zero indicates complete scalp regrowth, and roughly one in five patients on the higher dose achieved it.
Eyebrows and eyelashes matter more to many patients than the raw percentages suggest, both cosmetically and functionally, since eyelashes protect the eye. Both trials measured them separately and found significant improvement.
Alopecia areata is an autoimmune condition in which the immune system attacks hair follicles. It is not contagious, is not caused by stress alone, and is frequently dismissed as cosmetic despite documented effects on employment, social functioning, and mental health.
Safety Findings and the Class Context
Treatment-emergent adverse events occurred in 67.1% of patients on 30 mg, 62.7% on 15 mg, and 57.1% on placebo. The most common were upper respiratory tract infection, acne, elevated blood creatine phosphokinase, and nasopharyngitis.
Serious adverse events occurred in 2.3% at the higher dose, 1.6% at the lower dose, and 0.4% in the placebo group. No deaths were reported in either trial. Investigators characterized the safety profile as consistent with upadacitinib's existing approved indications, with no new signals identified.
That framing carries weight in both directions. Upadacitinib is already approved for several inflammatory conditions, including atopic dermatitis, so its safety profile is well characterized. But JAK inhibitors as a class carry boxed warnings from the FDA regarding serious infections, mortality, malignancy, major adverse cardiovascular events, and thrombosis.
Twenty-four weeks is a short window for detecting risks that accumulate over years. That is the central limitation here, and it is not a small one.
Who Stands to Gain Most If Approval Follows
Three oral JAK inhibitors are currently approved for severe alopecia areata: baricitinib, ritlecitinib, and deuruxolitinib. In the pivotal baricitinib trials, 38.8 percent and 35.9 percent of patients on the 4 milligram dose reached a SALT score of 20 or less, though at week 36 rather than week 24. Only ritlecitinib carries an adolescent indication, which leaves a real gap for younger patients.
These trials enrolled 118 adolescents aged 12 to 17, making the program one of the largest phase 3 evaluations of a JAK inhibitor in that age group. For teenagers with extensive hair loss, a period when appearance and peer relationships carry outsized weight, an additional option would matter.
Patients who did not respond adequately to an approved JAK inhibitor are the other group with a clear stake. There is currently no established sequence for what to try next.
Cost and coverage remain barriers regardless of how many drugs exist. Approved JAK inhibitors for alopecia areata commonly require prior authorization, documentation of severity, and sometimes failure of other therapies. Patients facing denials can ask a dermatologist about appeals, peer-to-peer review, and manufacturer assistance programs. The National Alopecia Areata Foundation maintains treatment and access resources.
Anyone currently taking a JAK inhibitor should not stop or change their dose based on these results without speaking to their prescriber.
A third study is underway evaluating long-term efficacy, safety, and dose adjustment through week 52 in both trials, and earlier reported week 52 figures show responses continuing to improve. Those longer data will do more to define where upadacitinib sits relative to the approved options than the 24-week results can. The manufacturer announced its FDA submission covering adults and adolescents with severe alopecia areata in April 2026. No action date has been announced publicly. Until a decision is issued, the approved options remain in effect.
Key Questions Answered
Is upadacitinib approved for alopecia areata?
No. An application is under FDA review. The drug is approved for other inflammatory conditions, but not for alopecia areata, and cannot be prescribed for it on label today.
What does a SALT score of 20 mean?
It corresponds to at least 80 percent scalp hair coverage. A score of 0 means complete scalp regrowth. Patients in these trials started at a mean score of 83.9.
How do these results compare with approved drugs?
Pivotal trials of baricitinib, ritlecitinib, and deuruxolitinib reported response rates between roughly 23 and 39 percent on the same threshold, at differing time points. These trials reported up to 55 percent, but no head-to-head comparison exists.
What were the main side effects?
Upper respiratory tract infection, acne, elevated creatine phosphokinase, and nasopharyngitis. Serious adverse events occurred in 2.3% at the higher dose versus 0.4% in the placebo group.
Are there long-term safety concerns with JAK inhibitors?
The class carries FDA boxed warnings covering serious infections, mortality, malignancy, cardiovascular events, and thrombosis. These trials ran for 24 weeks, which is too short to assess long-term risk.
Were adolescents included?
Yes. The trials enrolled 118 patients aged 12 to 17. Among currently approved oral JAK inhibitors for alopecia areata, only ritlecitinib carries an adolescent indication.
Should someone stop their current treatment because of these results?
No. Anyone taking an approved JAK inhibitor should continue as prescribed and discuss any change with their dermatologist.
