What JAK inhibitors changed for alopecia areata

A smooth, round patch behind the ear, spotted by the hairdresser. A few months later, two more. For some people, the hair loss spreads across the whole scalp, then the eyebrows and eyelashes. Since 2022, a family of tablets called JAK inhibitors has been approved for the severe forms of this condition, alopecia areata. What they achieve, what they ask of you in return, and who they are meant for.

Alopecia areata, a different condition

Alopecia areata is an autoimmune condition: the immune system, which should leave the follicle alone, attacks it and the hair falls out¹. It usually starts with a round or oval bald patch on the scalp or in the beard². It can spread to the whole scalp (alopecia totalis) and, more rarely, to all the hair on the body (alopecia universalis)².

About 2% of people will have it at some point in their life. It most often appears between the ages of 10 and 30, and in most cases before 40¹. It isn’t contagious². Nails are affected in 10 to 40% of people with the condition, with small pits on the surface, especially in more extensive forms¹. Other autoimmune conditions are a little more common in people who have it, such as thyroid disease, vitiligo or psoriasis¹.

The follicle isn’t destroyed, and hair can grow back on its own, sometimes white and finer at first². But relapses are common: many people have one within a year of regrowth, and most within five years². We cover what grows back after each type of hair loss in another article.

This isn’t common baldness, which depends on hormones and genes. JAK inhibitors are approved for severe alopecia areata, not for baldness³.

How these tablets work

Immune cells communicate through inflammatory messages. JAK inhibitors block some of these messages inside the cells, which calms the attack⁴. Each molecule has slightly different targets: baricitinib acts mainly on JAK1 and JAK2⁴. The same family is also used for rheumatoid arthritis and atopic eczema³.

Which medicines, and since when

• June 2022: baricitinib becomes the first to be approved in the US for severe alopecia areata in adults⁵. In Europe, it is now authorised for severe alopecia areata from age 12³.
• June 2023: ritlecitinib is approved in the US from age 12⁵. Europe follows on 15 September 2023, for adults and adolescents aged 12 and over⁶.
• July 2024: deuruxolitinib is approved in the US for adults⁵.

In the UK, NICE recommends ritlecitinib for severe alopecia areata from age 12, available through general dermatology clinics⁷.

Who they are for: what “severe” means

Dermatologists measure how extensive alopecia areata is with a score called SALT, from 0 (no scalp hair loss) to 100 (complete loss). For the British Association of Dermatologists, alopecia areata is severe when at least half the scalp is affected⁷.

Alopecia areata affecting 21 to 49% of the scalp can also be rated severe if at least one of these is present⁷:

• it affects your mental health or daily life;
• the eyebrows or eyelashes are noticeably involved;
• the response is still inadequate after at least six months of another treatment;
• the hair loss is progressing fast, with hairs coming out easily when gently pulled all over the scalp.

The same dermatologists advise assessing the psychological impact before starting, including suicide risk⁷. When patches appear quickly, other causes need ruling out: we list the causes a doctor checks first for sudden hair loss. The choice of treatment belongs to the dermatologist, together with you, after that assessment. If you’re not sure where to start, here’s which doctor to see about hair loss.

What the trials show

The two large baricitinib trials, BRAVE-AA1 and BRAVE-AA2, enrolled 654 and 546 adults with severe alopecia areata (at least half the scalp affected)⁸. They were randomly given a higher dose, a lower dose or a placebo for 36 weeks. The goal: get back at least 80% of their scalp hair, meaning a SALT score of 20 or less.

The European Medicines Agency sums up both trials, about 1,200 adults in all: 34% on the higher dose, 20% on the lower dose, 4% on placebo⁹. For ritlecitinib, 23% of treated people had more than 80% scalp hair coverage at 24 weeks, and 13% had more than 90%, against 1.5% on placebo⁶.

These results have limits. The trials lasted less than a year, and the authors themselves write that longer trials are needed to judge effectiveness and safety⁸. They were funded by the manufacturer⁸. And even on the higher dose, about two people in three didn’t reach the goal. British dermatologists also note lower response rates when severe disease has lasted a long time⁷.

Side effects

For baricitinib, the most frequent effects (more than one person in ten) are raised cholesterol and nose and throat infections⁹. Also common: headache, cold sores, urinary tract infections, shingles, nausea, acne, folliculitis (small spots around the hairs, often where hair is regrowing), and raised liver and muscle enzymes in blood tests³.

For ritlecitinib, the effects that affect up to one person in ten are diarrhoea, acne, upper respiratory tract infections, hives, rash, folliculitis and dizziness⁶.

Rarer but serious, for the whole family: severe infections, blood clots, cardiovascular events and some cancers⁴. That’s why the European agency says baricitinib should only be used, when no suitable alternative exists, in people aged 65 and over, people with cardiovascular disease or risk factors (including current or past long-term smoking) and people at risk of cancer³. Baricitinib must not be used during pregnancy³. Ritlecitinib must not be used during pregnancy or breastfeeding, nor with an active serious infection, including tuberculosis, or severe liver problems⁶.

Tests before, monitoring during

Before starting, the French Society of Dermatology describes a standard check-up⁴:

• a blood test (blood cells, liver, kidneys, cholesterol);
• depending on the case, screening for tuberculosis, hepatitis or HIV;
• bringing vaccinations up to date, because live vaccines are contraindicated during treatment.

After that, monitoring is regular, and closer after 65, in smokers and former smokers, and with cardiovascular risk or a history of cancer⁴. Effectiveness is reviewed at 36 weeks: with no regrowth at all, ritlecitinib is stopped; with some regrowth that falls short of the goal, treatment can be extended by three months⁷.

What happens when you stop?

British dermatologists warn that regrown hair is likely to fall out again when treatment stops, and that treatment is likely to be lifelong⁷. They recommend discussing this before starting, and planning psychological support if treatment has to stop, because going through the hair loss again can be very hard⁷. While hair regrows, a wig often remains useful⁷.

Long-term safety and what happens after stopping are still open questions, and these are expensive medicines¹. Alopecia areata can’t be cured yet, but it now has treatments tested in large trials.

Tracking regrowth with photos

In alopecia areata, regrowth is slow and uneven: one patch fills in with fuzz while another gets bigger. After a few months, it’s hard to remember where you started.

One photo a week, taken in the same conditions, solves that. In Calvap, you photograph the affected areas, and last week’s picture shows as an overlay so you can line up the shot. The journal keeps the date you started treatment, your blood tests and the effects you notice. At the 36-week review, you show the dermatologist dated photos, area by area.