Topic
JAK inhibitors and hair
Janus kinase (JAK) inhibitors are pills that regrow hair in severe alopecia areata, but they are not treatments for ordinary pattern thinning.
Key takeaways
- Three JAK inhibitors are approved for severe alopecia areata: baricitinib (US 2022; adolescents 12 and over from September 2026), ritlecitinib (US June 2023, EU September 2023; ages 12 and over) and deuruxolitinib (US July 2024; adults). Upadacitinib is under FDA and EMA review.
- Typical results: in 24-week phase 3 trials, at least 80% scalp hair was reached by about 20 to 55% on the studied doses (ritlecitinib 50 mg: 23%; baricitinib 4 mg: 35.9 to 38.8% at week 36; deuruxolitinib 8 mg: 29.6 to 33.0%; upadacitinib 15 and 30 mg: 45 to 55%) versus 0 to 6% on placebo. Cross-trial comparisons are indirect because populations and counting differ.
- Responses grow over time: 65.1% of ritlecitinib users had at least 80% scalp hair at 3 years (Senna 2026).
- They suppress, not cure: by week 152 of a randomised withdrawal, 80% of baricitinib responders switched to placebo had lost benefit versus 7% who stayed on drug (King 2024); a meta-analysis of older tofacitinib and ruxolitinib data found 74% relapsed within 3 months (Yu 2021).
- Serious class risks: infections, blood clots, cardiovascular events and cancer warnings. Pregnancy is a contraindication for ritlecitinib in the EU. Specialist supervision only.
- Topical JAK failed for alopecia areata: ruxolitinib cream did no better than vehicle in a phase 2 trial (Olsen 2020).
- Cost is high: the US list price for baricitinib was about $2,497 per 30 days in 2022. In the UK, NICE recommends ritlecitinib and deuruxolitinib but did not recommend baricitinib.
- No evidence for pattern hair loss: no controlled trial of any JAK inhibitor in androgenetic alopecia was found.
The science
Alopecia areata is an autoimmune attack by T cells on hair bulbs, driven by interferon-gamma and related cytokines that all signal through JAK enzymes. Mouse work and three patients on oral ruxolitinib in 2014 first showed that blocking JAKs reverses it (Xing 2014).
Different drugs hit different JAKs: baricitinib and deuruxolitinib JAK1 and JAK2; ritlecitinib JAK3 plus TEC kinases; tofacitinib JAK1 and JAK3; upadacitinib JAK1. Whether this changes efficacy or safety is unproven; an indirect comparison found no clear difference between ritlecitinib 50 mg and baricitinib 4 mg (Aceituno 2025).
A 2023 meta-analysis of 7 RCTs (1,710 people) found oral JAK inhibitors clearly beat placebo while topical ones did not (Liu 2023), and a Cochrane review judged baricitinib the only alopecia areata treatment with high-certainty benefit (Mateos-Haro 2023).
Comparison
| Drug | Target | Status (10 Oct 2026) | At least 80% scalp hair | Dosing |
|---|---|---|---|---|
| Baricitinib | JAK1/2 | FDA 2022 (adults), adolescents Sept 2026; EU adults and 12+; UK licensed, NICE no | 38.8% and 35.9% (4 mg, week 36) vs 6.2% and 3.3% (King 2022) | 2 or 4 mg once daily |
| Ritlecitinib | JAK3/TEC | FDA 2023 (12+), EU 2023 (12+), UK yes | 23% (50 mg) vs 2% (week 24) (King 2023) | 50 mg once daily |
| Deuruxolitinib | JAK1/2 | FDA 2024 (adults); NICE July 2026; no EU filing found | 29.6 to 33.0% (8 mg) vs 0.8% (King 2024; Tsianakas 2026) | 8 mg twice daily |
| Upadacitinib | JAK1 | Under FDA and EMA review | 45% (15 mg), 55% (30 mg) vs 1.5 to 3.4% (Mostaghimi 2026) | 15 or 30 mg once daily |
| Tofacitinib | JAK1/3 | Off-label | Open-label: 32% (66 people) to 66% (meta-analysis) improved by 50% | 5 mg twice daily |
| Ruxolitinib | JAK1/2 | Off-label (pill); cream failed | 9 of 12 in a pilot | 20 mg twice daily |
What it means by hair profile
- Not hair-type specific. What matters is age (ritlecitinib and baricitinib cover adolescents), extent (at least half the scalp in the trials), and episode length: shorter episodes respond better, and female sex was associated with better response in an extension analysis, a subgroup finding (Senna 2026).
- Eyebrows and eyelashes also regrow: in baricitinib trials week-36 eyebrow response was 44.3% versus 12.6% on placebo (Mostaghimi 2025).
- No data show whether texture or curl changes after regrowth.
Myths and facts
- Myth: JAK inhibitors are the new minoxidil for everyone. Fact: only severe alopecia areata is approved; cost, infection screening and class warnings limit them.
- Myth: regrowth is permanent. Fact: relapse is the rule on stopping.
- Myth: topical JAK creams are a safe version. Fact: ruxolitinib cream failed in alopecia areata.
Practical recommendations
- For patchy alopecia areata, see a dermatologist first: steroids and other local treatments come before JAK inhibitors. The European consensus describes a SALT score of 20 or more (at least a fifth of the scalp affected) as a common threshold for considering systemic treatment (Rudnicka 2024).
- These drugs need screening (tuberculosis, hepatitis, blood tests), contraception planning and follow-up. Costs and access differ widely by country.
Bottom line
JAK inhibitors are the first proven systemic treatments for severe alopecia areata and work only while you take them. They are not for pattern thinning. Discuss with a doctor.
Studies 15
Xing L et al. Alopecia areata is driven by cytotoxic T lymphocytes and is reversed by JAK inhibition. Nat Med. 2014
Tested: JAK inhibitors, including oral ruxolitinib
Result: Systemic JAK inhibitors prevented disease in mice, topical ones reversed it, and three patients on ruxolitinib regrew nearly all hair within 5 months.
Read the study ↗Aceituno D et al. Systematic review and indirect treatment comparisons of ritlecitinib against baricitinib in alopecia areata. J Eur Acad Dermatol Venereol. 2025
Tested: ritlecitinib 50 mg vs baricitinib 4 mg, indirect
Result: No evidence of a difference at week 24, with wide uncertainty; the authors are Pfizer-affiliated.
Read the study ↗Liu M et al. Janus kinase inhibitors for alopecia areata: a systematic review and meta-analysis. JAMA Netw Open. 2023
Tested: oral and topical JAK inhibitors vs placebo
Result: Oral JAK inhibitors beat placebo (odds ratio 8.15 for 90% improvement); topical ones did not.
Read the study ↗Mateos-Haro M et al. Treatments for alopecia areata: a network meta-analysis. Cochrane Database Syst Rev. 2023
Tested: all studied treatments
Result: Baricitinib was the only treatment with high-certainty evidence of benefit; for oral prednisolone or cyclosporine versus placebo the evidence was very uncertain.
Read the study ↗Senna M et al. Long-term efficacy and safety of ritlecitinib in alopecia areata: 3-year results. Am J Clin Dermatol. 2026
Tested: ritlecitinib 50 mg daily
Result: At least 80% scalp hair at 3 years in 65.1% observed (47.1% with missing data carried forward); 88 to 90% of year-1 responders kept it.
Read the study ↗Rudnicka L et al. European expert consensus statement on the systemic treatment of alopecia areata. J Eur Acad Dermatol Venereol. 2024
Tested: systemic treatments for alopecia areata
Result: Lists off-label glucocorticoids, methotrexate, cyclosporine and azathioprine alongside approved JAK inhibitors.
Read the study ↗Show 9 more studies
King B et al. Two phase 3 trials of baricitinib for alopecia areata. N Engl J Med. 2022
Tested: baricitinib 2 mg or 4 mg daily vs placebo
Result: At least 80% scalp hair at week 36: 38.8% (4 mg), 22.8% (2 mg), 6.2% (placebo) in trial 1; 35.9%, 19.4%, 3.3% in trial 2.
Read the study ↗King B et al. Efficacy and safety of ritlecitinib in adults and adolescents with alopecia areata: a randomised, double-blind, multicentre, phase 2b-3 trial. Lancet. 2023
Tested: ritlecitinib 10, 30 or 50 mg daily, with or without a 200 mg loading dose, vs placebo
Result: At least 80% scalp hair at week 24 in 23% on 50 mg vs 2% on placebo, and 31% with the loading dose; Pfizer-funded.
Read the study ↗King B et al. Efficacy and safety of deuruxolitinib in adults with severe alopecia areata: THRIVE-AA1 phase 3 randomized, controlled trial. J Am Acad Dermatol. 2024
Tested: deuruxolitinib 8 mg or 12 mg twice daily vs placebo
Result: At least 80% scalp hair in 29.6% (8 mg), 41.5% (12 mg) and 0.8% (placebo); Sun-funded.
Read the study ↗Tsianakas A et al. Deuruxolitinib in severe alopecia areata: THRIVE-AA2 phase 3 trial. J Am Acad Dermatol. 2026
Tested: deuruxolitinib 8 mg or 12 mg twice daily vs placebo
Result: At least 80% scalp hair at week 24 in 33.0% (8 mg), 38.3% (12 mg) and 0.8% (placebo).
Read the study ↗Mostaghimi A et al. Upadacitinib for severe alopecia areata in adults and adolescents: two phase 3 UP-AA randomized clinical trials. JAMA Dermatol. 2026
Tested: upadacitinib 15 mg or 30 mg daily vs placebo
Result: At least 80% scalp hair at week 24 in 45.2% and 44.6% (15 mg), 55.0% and 54.3% (30 mg) vs 1.5% and 3.4% on placebo; sponsor-funded.
Read the study ↗King B et al. Baricitinib withdrawal and retreatment in patients with severe alopecia areata: the BRAVE-AA1 randomized clinical trial. JAMA Dermatol. 2024
Tested: continuing baricitinib vs switching to placebo, then retreatment
Result: By week 152, 80% of responders switched to placebo had lost benefit vs 7% who stayed on drug; retreatment recaptured response in most.
Read the study ↗Olsen EA et al. Ruxolitinib cream for the treatment of patients with alopecia areata. J Am Acad Dermatol. 2020
Tested: ruxolitinib 1.5% cream vs vehicle
Result: The open-label part looked promising, but the double-blind part showed no significant difference from vehicle.
Read the study ↗Yu DA et al. Treatment outcome of oral tofacitinib and ruxolitinib in patients with alopecia areata. Indian J Dermatol Venereol Leprol. 2021
Tested: oral tofacitinib or ruxolitinib
Result: At least 50% improvement in 66%; 74% relapsed within 3 months of stopping; infections and lab abnormalities were the commonest problems.
Read the study ↗Mostaghimi A et al. Understanding eyebrow and eyelash involvement in patients with alopecia areata and responsiveness to treatment with baricitinib. Br J Dermatol. 2025
Tested: baricitinib 4 mg vs placebo
Result: Eyebrow response was 44.3% vs 12.6% and eyelash response 46.4% vs 12.4% at week 36.
Read the study ↗Related
- BaricitinibA once-daily pill that was the first drug approved for severe alopecia areata, regrowing hair in about a third of patients while they keep taking it.
- RitlecitinibA once-daily pill approved for severe alopecia areata from age 12, which regrows hair in about 1 in 4 people by 6 months and keeps improving for years.
- DeuruxolitinibA twice-daily JAK pill approved in the US in 2024 for adults with severe alopecia areata, giving about 3 in 10 people near-full scalp hair at 24 weeks.
- UpadacitinibA JAK1 pill already approved for other diseases that gave 45 to 55% of people with severe alopecia areata near-full scalp hair in two 2026 trials and is under regulatory review for hair.
- TofacitinibThe first JAK inhibitor used off-label for alopecia areata; about a third to two thirds of patients regrow hair in open-label studies, but most relapse within months of stopping.
- RuxolitinibThe JAK1/2 blocker whose first use in three alopecia areata patients in 2014 launched the JAK era for hair; the pill regrows hair in small studies while the cream failed.
- Alopecia areataAn autoimmune condition where the immune system attacks growing hair follicles, causing round patches or total hair loss; three oral JAK inhibitors are approved for severe cases but hair usually goes again when treatment stops.
- Hair growth pipeline (2026)What is in clinical trials for hair loss as of October 2026, how far along it is, and how much to trust the early numbers.