JAK inhibitors for alopecia: baricitinib, ritlecitinib, and what lies ahead

For years, dermatologists had little to offer beyond injectable corticosteroids or broad immunosuppressants. Results were hit-and-miss, and both patients and clinicians found it frustrating.

Between 2022 and 2023, two oral JAK pathway inhibitors, baricitinib and ritlecitinib, changed the picture for severe alopecia areata. In 7 to 12% of patients, the disease progresses to total loss of scalp hair, eyebrows, and eyelashes. The psychological impact is hard to overstate.

Understanding what these drugs can and can’t do puts you in a better position when talking to your doctor.

What happens in the follicle when alopecia areata develops

You don’t need a background in immunology to follow this. The basic mechanism is fairly straightforward.

During its growth phase, the hair follicle is normally shielded by what specialists call “immune privilege.” In practice, follicle cells become near-invisible to the immune system. They express very few identifying proteins (MHC class I molecules) and sit within an anti-inflammatory environment. The hair cycle ticks along as normal.

In alopecia areata, this protective barrier breaks down. Follicles start expressing alarm molecules (notably ULBP3), and cytotoxic T lymphocytes detect them. A targeted inflammatory attack follows.

What makes the condition hard to treat is the self-reinforcing loop that develops. T cells release interferon-gamma, which drives more inflammation, which activates more T cells. This cycle runs entirely through the JAK-STAT signalling pathway. Three JAK proteins are involved: JAK1 and JAK2 on the follicle side, JAK3 on the T cell side.

Hair is then forced out of its growth phase prematurely, entering regression and then a prolonged resting phase. Unlike scarring alopecia, where follicles are permanently destroyed, the follicles in alopecia areata remain intact. Dormant, but not dead.

Regrowth is therefore possible once inflammation is controlled. Block the JAK proteins and you break the cycle at its source, letting the follicle regain its immune privilege and restart normal growth. That, in short, is what JAK inhibitors do.

Baricitinib: the first approved oral treatment for alopecia areata

Baricitinib (Olumiant®) targets JAK1 and JAK2. It was originally developed for rheumatoid arthritis and became the first oral medication approved for severe alopecia areata in adults, receiving FDA approval in June 2022 with European and UK authorisation following shortly after. For a condition that pharma had largely ignored, this mattered.

Two large trials support the approval: BRAVE-AA1 and BRAVE-AA2, involving more than 1,200 adults with at least 50% scalp hair loss. These were patients with severe to very severe disease; more than half had near-total alopecia.

The results: at 36 weeks, roughly 35% of patients on baricitinib 4 mg had regained at least 80% scalp coverage. Response continued to improve with time. By week 52, the figure reached 40.9% in BRAVE-AA1 and 36.8% in BRAVE-AA2. Some patients who showed no early response went on to improve with continued treatment, so it’s worth sticking with it.

But alopecia areata remains a chronic condition, and the withdrawal data make that clear. After a year of effective treatment, 80% of patients who stopped baricitinib relapsed. The encouraging part: restarting works. Among those retreated at 4 mg, 87.5% regained a good response.

Side effects are broadly what you’d expect from an oral immunomodulator: upper respiratory infections, headaches, nasopharyngitis, acne. These were generally well tolerated. Four years of continuous safety data showed no new signals, no opportunistic infections, and no serious cardiovascular events.

Ritlecitinib: more targeted, and available from age 12

Ritlecitinib (Litfulo®) works differently. Rather than targeting JAK1/JAK2, this Pfizer molecule selectively inhibits JAK3 and TEC family kinases. The idea is to act closer to the offending T cells while leaving other signalling pathways alone.

The FDA approved it in June 2023, and it’s also authorised in the UK. What matters most about ritlecitinib is that it’s licensed from age 12, making it the first JAK inhibitor available to adolescents for alopecia areata. That’s important, because the condition often starts young.

The ALLEGRO trial recruited 718 patients across 18 countries. At 50 mg daily, with or without a 200 mg loading dose for the first four weeks, results were significant from week 24 compared to placebo, and continued to improve over subsequent months.

The long-term figures stand out. The ALLEGRO-LT study followed 449 patients for two years: 73.5% achieved a SALT score of 20 or below (meaning at least 80% hair coverage) and 66.4% reached a SALT score of 10 or below (near-complete coverage). More than 82% of patients rated their improvement as moderate to significant.

Ritlecitinib also helped with eyebrow and eyelash regrowth. For someone who hasn’t had eyebrows for years, that’s no small thing.

On the safety front, the main adverse events were nasopharyngitis, folliculitis, and upper respiratory infections. No cardiovascular, thromboembolic, or tumour-related events were reported in the ALLEGRO programme.

Baricitinib or ritlecitinib: which one?

It depends on the patient. Baricitinib targets JAK1/JAK2 and is for adults only. Ritlecitinib targets JAK3/TEC and is licensed from age 12. Both require ongoing treatment to maintain results.

In practice, the dermatologist decides based on age, comorbidities, previous treatments, and how severe the alopecia is. A teenager will usually be offered ritlecitinib. An adult with coexisting rheumatoid arthritis might do well on baricitinib. Both need a prescription and regular blood monitoring.

A third molecule, deuruxolitinib (Leqselvi®), also received FDA approval in July 2024. The options are growing.

When medication isn’t enough

JAK inhibitors have made a real difference for many patients with alopecia areata. But they’re not for everyone. Some people don’t respond. Others have contraindications. And relapse after stopping treatment is near-certain, which is something to discuss honestly with your dermatologist before starting.

Something that often trips people up: alopecia areata and androgenetic alopecia are completely different conditions. Alopecia areata is autoimmune, driven by immune dysfunction. Androgenetic alopecia is hormonal and genetic, causing progressive thinning in specific areas of the scalp. The biology is different, and so are the treatments.

For stabilised androgenetic alopecia, a hair transplant in Turkey remains the most effective long-term option. Dr Emrah Cinik’s clinic, with over 20 years of experience in Istanbul, offers well-established techniques: Sapphire FUE, DHI, with PRP treatment and Regenera Activa included in treatment packages to support regrowth.

If you’re unsure whether your situation calls for a medical or surgical approach, a free consultation can help clarify things. For more on hair loss treatments, see our full guide or get in touch.

Scientific references

King, B., Ohyama, M., Kwon, O., et al. (2022). Two phase 3 trials of baricitinib for alopecia areata. New England Journal of Medicine, 386(18), 1687-1699.

Kwon, O., Senna, M. M., Sinclair, R., et al. (2023). Efficacy and safety of baricitinib in patients with severe alopecia areata over 52 weeks of continuous therapy in two phase III trials (BRAVE-AA1 and BRAVE-AA2). American Journal of Clinical Dermatology, 24(3), 443-451. https://pmc.ncbi.nlm.nih.gov/articles/PMC9974384/

King, B., Zhang, X., Harcha, W. G., et al. (2023). Efficacy and safety of ritlecitinib in adults and adolescents with alopecia areata: a randomised, double-blind, multicentre, phase 2b-3 trial. The Lancet, 401(10387), 1518-1529. https://pubmed.ncbi.nlm.nih.gov/37062298/

Tziotzios, C., Sinclair, R., Lesiak, A., et al. (2025). Long-term safety and efficacy of ritlecitinib in adults and adolescents with alopecia areata and at least 25% scalp hair loss: Results from the ALLEGRO-LT phase 3, open-label study. Journal of the European Academy of Dermatology and Venereology, 39(6), 1152-1162. https://pmc.ncbi.nlm.nih.gov/articles/PMC12105460/

King, B., Senna, M. M., Ohyama, M., et al. (2024). Baricitinib withdrawal and retreatment in patients with severe alopecia areata: The BRAVE-AA1 randomized clinical trial. JAMA Dermatology, 160(10), 1039-1048. https://pmc.ncbi.nlm.nih.gov/articles/PMC11325239/

Jabbari, A. (2022). An overview of JAK/STAT pathways and JAK inhibition in alopecia areata. Frontiers in Immunology, 13, 955035. https://pmc.ncbi.nlm.nih.gov/articles/PMC9470217/

Mysore, V., et al. (2023). Which is the ideal JAK inhibitor for alopecia areata – baricitinib, tofacitinib, ritlecitinib or ifidancitinib. Journal of Cutaneous and Aesthetic Surgery, 16(1), 1-11. https://pmc.ncbi.nlm.nih.gov/articles/PMC10373824/