JAK Inhibitors for Alopecia Areata: Baricitinib, Ritlecitinib and the Evidence

JAK inhibitors are tablets that calm the immune attack on hair follicles in alopecia areata. They are the first treatments proven in large trials to regrow hair in severe cases. In phase 3 trials, about 30 to 40% of patients who had lost at least half their scalp hair regained at least 80% coverage on the higher doses, against under 7% on placebo ^[2,5]. In Switzerland, baricitinib and ritlecitinib are authorised for severe alopecia areata ^[12,13].

In short: JAK inhibitors work for many, but not all, patients with severe alopecia areata. They need months to act, must usually be continued to keep the hair, and require blood tests and monitoring by a dermatologist. A hair transplant is not a solution for active alopecia areata.

What is alopecia areata, and how do JAK inhibitors help?

Alopecia areata is an autoimmune disease: immune cells attack hair follicles, causing round bald patches or, in severe forms, loss of all scalp hair (alopecia totalis) or all body hair (alopecia universalis). The follicles are not destroyed, which is why hair can regrow.

Janus kinases (JAKs) are signalling enzymes inside immune cells. Blocking them interrupts the inflammatory signals that drive the attack. The drugs in this guide differ in which kinases they block:

Drug	Targets	Dose in trials	Status in Switzerland
Baricitinib (Olumiant)	JAK1/JAK2	2 or 4 mg once daily	Authorised for severe AA in adults up to 60 [13]
Ritlecitinib (Litfulo)	JAK3/TEC	50 mg once daily	Authorised since 3 Feb 2025, ages 12–65 [12]
Deuruxolitinib	JAK1/JAK2	8 or 12 mg twice daily	Ask your dermatologist about availability

How severity is measured: the SALT score

Trials use the Severity of Alopecia Tool (SALT), which scores scalp hair loss from 0 (no hair loss) to 100 (complete loss) ^[2]. The usual trial target is SALT 20 or less, meaning at least 80% of the scalp is covered. A European expert consensus considers a SALT score of 20 or more a common indication for systemic treatment ^[1].

Key trials at a glance

Trial	Design	n	Result (SALT ≤20)
BRAVE-AA1 & AA2, baricitinib, NEJM 2022 [2]	Two phase 3 RCTs, 36 weeks	1,200	4 mg: 38.8% and 35.9%; 2 mg: 22.8% and 19.4%; placebo: 6.2% and 3.3%
BRAVE-AA1 withdrawal, JAMA Dermatol 2024 [4]	Randomised withdrawal after 52 weeks	154 responders	80% lost response by week 152 after stopping vs 7% who continued
ALLEGRO, ritlecitinib, Lancet 2023 [5]	Phase 2b/3 RCT, 24 weeks, age 12+	718	50 mg: 23%; 200/50 mg: 31%; placebo: 2%
ALLEGRO-LT, BJD 2025 [6]	Long-term extension	385	50 mg: 45% at 12 months, 61% at 24 months (observed)
THRIVE-AA1, deuruxolitinib, JAAD 2024 [8]	Phase 3 RCT, 24 weeks	–	8 mg: 29.6%; 12 mg: 41.5%; placebo: 0.8%
THRIVE-AA2, deuruxolitinib, JAAD 2026 [9]	Phase 3 RCT, 24 weeks	517	8 mg: 33.0%; 12 mg: 38.3%; placebo: 0.8%

Baricitinib: the BRAVE-AA trials

The two BRAVE-AA trials enrolled 1,200 adults with SALT scores of 50 or higher. After 36 weeks, 36 to 39% on 4 mg reached SALT 20 or less, compared with 19 to 23% on 2 mg and 3 to 6% on placebo ^[2]. A Cochrane review rated the evidence that baricitinib increases both short- and long-term hair regrowth as high-certainty. For other alopecia areata treatments, the evidence was very uncertain ^[3].

In Switzerland, the recommended starting dose is 4 mg, reduced to 2 mg once a stable response is reached. Treatment should be stopped if there is no meaningful response (at least 25% SALT improvement) after 36 weeks. It should generally not continue beyond one year unless the benefit clearly outweighs the risks ^[13].

Ritlecitinib: the ALLEGRO trials

Ritlecitinib was tested in 718 patients aged 12 and older with at least 50% scalp hair loss. At 24 weeks, 23% on the 50 mg dose and 31% on a 200 mg loading dose followed by 50 mg reached SALT 20 or less, versus 2% on placebo ^[5]. Results kept improving with longer use: among patients on 50 mg, 45% had reached the target at one year and 61% at two years (observed data). Eyebrow and eyelash regrowth also increased ^[6]. Ritlecitinib is the only option in this group authorised from age 12 ^[12].

Deuruxolitinib: the THRIVE-AA trials

Deuruxolitinib was tested in two phase 3 trials in adults aged 18 to 65. At 24 weeks, 30 to 42% of patients reached SALT 20 or less on deuruxolitinib, compared with 0.8% on placebo ^[8,9]. Satisfaction with hair growth tracked the objective results ^[8]. Both trials were short, and long-term durability has not yet been reported ^[9].

Side effects and safety

JAK inhibitors suppress parts of the immune system, so monitoring matters.

• Baricitinib: acne, raised creatine kinase and higher LDL and HDL cholesterol were more common than with placebo ^[2].
• Ritlecitinib: in 1,294 patients followed for a median of 624 days, serious side effects occurred in 4.4% and 6.0% stopped because of side effects. Headache was the most common. Shingles (herpes zoster) affected 1.5%, cancer (excluding non-melanoma skin cancer) 0.5%, and major cardiovascular events 0.2% ^[7].
• Deuruxolitinib: most side effects were mild or moderate ^[8,9].

A meta-analysis of seven trials found that JAK inhibitors were not linked to more severe side effects than placebo ^[10]. Another, covering 35 trials in skin diseases, found no significant increase in heart attacks, strokes, deaths or blood clots. However, follow-up averaged only about five months ^[11].

The Swiss product information for baricitinib nevertheless carries a boxed warning on serious infections, mortality, cancer, major cardiovascular events and blood clots. It is based largely on a large trial of another JAK inhibitor in patients with rheumatoid arthritis aged 50 or older with cardiovascular risk factors. For patients over 65, it should be used only if no suitable alternatives exist ^[13]. Before starting, expect screening for tuberculosis and hepatitis, blood counts, liver values and lipids, and a review of vaccinations.

Relapse: why treatment is usually long term

Alopecia areata is chronic and relapsing. In the BRAVE-AA1 withdrawal study, responders who stopped baricitinib after one year mostly lost their regrowth: 80% had lost benefit by week 152, compared with 7% of those who stayed on treatment. Most who restarted regained a good response ^[4]. In practice, JAK inhibitors control the disease rather than cure it.

Why a hair transplant is not suitable for active alopecia areata

Hair transplants are designed for pattern hair loss, where follicles in the donor area are genetically resistant. In alopecia areata the problem is an immune attack that can affect any follicle, including transplanted ones. Bald patches may also regrow by themselves or with treatment. Hair surgeons therefore generally advise against transplanting in active alopecia areata. If you are unsure which type of hair loss you have, see a dermatologist before consulting a clinic. Our hair transplant guide explains who is a good candidate.

How strong is the evidence?

• Efficacy: strong. Several large, double-blind phase 3 RCTs exist for three drugs, and Cochrane rates the baricitinib evidence as high-certainty ^[2,3,5,8,9].
• Long-term outcomes: moderate. Extension studies run up to two to three years, but they are open-label and partly based on observed data ^[6].
• Long-term safety: uncertain. Trials are short relative to lifelong disease, and serious risks are rare events. The boxed warnings rely on data from other diseases and older populations ^[11,13].
• Head-to-head data: none. There are no trials comparing the JAK inhibitors directly, so it is unclear which is best for whom.
• Industry funding: the pivotal trials were funded by the manufacturers ^[2,5].

For an overview of the evidence for all hair loss treatments, see our evidence review.

Practical steps in Switzerland

1. Get a diagnosis from a dermatologist, ideally one with a hair clinic.
2. Ask whether your severity (usually at least 50% scalp loss) and age fit the Swiss label.
3. Clarify cost coverage with your health insurer in advance. These are expensive medicines; read our guide on health insurance.
4. Plan for regular blood tests and follow-up visits.

Patchy, mild alopecia areata is usually treated locally first, for example with steroid injections. JAK inhibitors are intended for severe forms.