Alopecia areata

Key takeaways

• Follicles are attacked, not destroyed. Alopecia areata (AA) is non-scarring, so regrowth is possible, including spontaneous regrowth in milder disease. It is different from androgenetic alopecia and telogen effluvium and can coexist with them.
• It is common and more often diagnosed in women. In a US claims study prevalence rose from 0.199% (2016) to 0.222% (2019), and roughly 5 to 10% of cases were total scalp or body hair loss (Mostaghimi 2023).
• It travels with other autoimmune and mood conditions. A meta-analysis of 102 studies found raised odds of vitamin D deficiency, lupus (OR 5.5), vitiligo (OR 5.3), metabolic syndrome (OR 5.0) and Hashimoto thyroiditis (OR 4.3) (Ly 2023). A US cohort found more psychiatric (30.9% vs 26.8%) and autoimmune (16.1% vs 8.9%) conditions at diagnosis (Mostaghimi 2024). Thyroid disease is about 3.7 times more frequent in AA (Xin 2020); see thyroid and hair.
• Oral JAK inhibitors are the first drugs proven to reverse severe AA. A 2026 meta-analysis of 12 trials (4,141 people) found the odds of reaching a scalp-hair score of SALT 10 or less at week 24 were 5.7 times higher than placebo, with no significant excess of serious adverse events (OR 1.04) but more adverse events overall (OR 1.60) (Morriss 2026).
• Cochrane rates baricitinib alone as high-certainty. Among all AA treatments tested in 63 randomized studies (4,817 people), only baricitinib had high-certainty evidence of benefit (RR 7.54 for 75% or more regrowth in the short term). Most older treatments, including steroids, immunotherapy, minoxidil and cyclosporine, rest on very-low to low-certainty evidence (Mateos-Haro 2023).
• They are for severe disease only, are prescription-only, and carry boxed warnings in the US covering serious infections, cancer, major cardiovascular events and blood clots.
• Stopping usually means relapse. These drugs suppress AA; they do not cure it.
• JAK inhibitors have no proven role in pattern hair loss (see JAK inhibitors and hair).

How it works

Growing follicles normally escape immune surveillance. In AA this breaks down, autoreactive T cells attack the bulb, and signalling through JAK enzymes sustains the attack. JAK inhibitors interrupt that signalling. Patchy AA shows as one or several round smooth patches; ophiasis is a band at the nape and sides; alopecia totalis is the whole scalp and alopecia universalis all body hair. Brows, lashes and nails can be involved. Severity is scored with SALT (0 = none, 100 = complete scalp loss); severe in trials means SALT 50 or more.

What the studies show

The US approved deuruxolitinib at 8 mg twice daily. In the ritlecitinib extension, 65.1% of observed patients had SALT 20 or less at 3 years (47.1% by the more cautious last-observation method) (Senna 2026). All pivotal trials were industry-funded and there are no head-to-head comparisons, so cross-trial comparisons are unreliable. Approval status differs by region (baricitinib and ritlecitinib are approved in the US, EU and UK; deuruxolitinib in the US and, from 2026, the UK; NHS access varies) and all three are prescription-only.

Other treatments:

• Topical or injected corticosteroids are the usual first step for limited patches. The German guideline gives topical corticosteroids its main topical recommendation and offers JAK inhibitors to adults, with other options for children and teens (Blume-Peytavi 2026).
• Topical minoxidil had RR 2.31 versus placebo in two small studies, with very-low-certainty evidence (Mateos-Haro 2023).
• Microneedling and PRP have small, low-quality AA data. Camouflage options include wigs, brow tattooing and scalp micropigmentation, and counselling helps.

Side effects and safety

Oral JAK inhibitors are linked to serious infections, shingles, blood clots, cardiovascular events, cancer and lab changes in lipids and creatine kinase (Morriss 2026). Common effects include headache and acne. Screening, vaccination and monitoring belong to the prescriber, and pregnancy is a concern with JAK inhibitors generally.

Hair type notes

• Any hair type can be affected; patches are easiest to spot in short or straight hair, and tight styles over a patch can add traction injury (traction alopecia).
• AA scalps are usually normal-looking and not scaly. Flaking or scarring points to other diagnoses such as tinea capitis or lichen planopilaris.
• Only some JAK inhibitors are licensed for ages 12 and up.
• No good evidence shows that stress alone, diet or supplements cause or cure AA.

Bottom line

See a doctor for any sudden patch, scarring, pain or rapid loss; blood tests for thyroid and vitamin D are commonly done. Mild patchy AA often regrows, and corticosteroids are the usual first step. For severe or long-lasting loss, a dermatologist can discuss JAK inhibitors, their monitoring, cost and the relapse risk. Support for mood matters too. Discuss with a doctor.