Alopecia Areata: Symptoms, Causes and Treatment (Including JAK Inhibitors)

A healthy hair follicle in the growth phase is a so-called immune-privileged site — the immune system normally ‘does not see’ it. In alopecia areata this protection is breached: T lymphocytes (especially cytotoxic ones) flow into the area of the follicle, and inflammatory signals, including those transmitted via the JAK-STAT pathway, maintain and intensify the immune response. The follicle is not destroyed but prematurely enters the resting phase and stops producing a visible hair. Because the follicle's stem cells are spared, regrowth remains possible — which is why alopecia areata is classed among non-scarring alopecias.

The exact causes are not fully known. A combination of genetic predisposition (the disease is more common in families) and environmental and immune factors that trigger it in predisposed people is assumed. Suggested triggers include infections, severe stress, injuries or hormonal changes, but the evidence for a causal role of individual factors is limited, and in most people no single specific reason can be identified.

The most common form is single or multiple patches on the scalp (patchy type). Rarer and more severe forms are: ophiasis (a band of hair loss along the hairline at the back and sides of the head, usually with a worse prognosis), alopecia totalis (loss of hair on the entire scalp) and alopecia universalis (loss of hair on the whole body). Severity is most often assessed with the SALT score (Severity of Alopecia Tool), in which 0 means no hair loss on the scalp and 100 means complete loss.

Characteristic of the disease are so-called exclamation-mark hairs (thinner towards the base, with a widened tip) visible at the edge of the patch, and nail changes — small pits, thinning, ridging. In trichoscopy (examination with a dermatoscope) the doctor sees yellow dots, black dots and exclamation-mark hairs, which usually allows the diagnosis to be confirmed without a biopsy. It is important to distinguish it from scalp ringworm, scarring alopecia and trichotillomania (habitual hair pulling), because each of these requires different management.

The course of alopecia areata is highly variable and hard to predict. In some people, especially with small single patches, hair regrows spontaneously over months, often first as thin, light hair and later of normal colour. In others the disease relapses in waves, may last for years or spread. The prognosis is usually worse with extensive patches, an ophiasis pattern, early onset, nail changes, coexisting atopy or other autoimmune diseases, and a long duration of the loss.

There is no way to predict precisely for a specific person whether and when hair will regrow, so a conversation about expectations is part of treatment. In the German S3 guideline, the first part of the document covers, among other things, definition, epidemiology and diagnosis, as well as comorbidities, risk and prognostic factors; the second — treatment and psychosocial and cosmetic support, which we describe below.

Practical conclusion for the patient: alopecia areata is not a disease of ‘the scalp alone’. In a person with newly diagnosed alopecia areata it is worth considering a thyroid assessment (TSH and, where indicated, anti-TPO antibodies — we write about the links between the thyroid and other autoimmune diseases in the entry on Hashimoto's disease and in the article on anti-TPO) and paying attention to signs of atopy and vitiligo. An increase in the odds of coexistence does not mean, however, that most people with alopecia areata have thyroid disease — this affects a minority.

Low vitamin D is common in the general population, particularly in Poland outside summer, so measuring it and correcting a deficiency makes health sense regardless of hair (details in the entry on vitamin D3). There is, however, no strong evidence that vitamin D supplementation alone restores hair in alopecia areata; we treat it as part of general care, not as treatment of the disease.

In practice the choice of therapy depends on the extent of the disease, age, duration and the patient's preferences. For small patches, topical corticosteroids are used (often also as injections into the patch — an approach used in dermatology, although detailed comparisons lie outside the scope of this article). For extensive disease systemic treatment is considered: short courses of steroids, methotrexate or JAK inhibitors. At the level of the German guideline, topical agents other than steroids have a low level of recommendation, including commonly used ones such as minoxidil, which does not replace anti-inflammatory treatment but is sometimes added as support.

What follows from this? First, JAK inhibitors are the first drugs that in large randomized trials showed the ability to restore hair in severe alopecia areata — the percentage of people with almost full regrowth was about 15–40% depending on the drug, dose and trial, versus a few percent on placebo. Second, it also means that most patients do not reach this best result in the first year, and some respond partially. Third, these are drugs taken continuously or for a long time, and stopping them is usually associated with a risk of relapse (an inference from the disease mechanism that requires an individual conversation with the doctor).

In the European Union both ritlecitinib (authorised in September 2023) and baricitinib are currently registered for the treatment of severe alopecia areata in adults and adolescents from 12 years of age. Treatment with these drugs requires qualification and monitoring by a doctor: before starting, infections, blood parameters and lipids are assessed, among other things, and during treatment attention is paid to infections and cardiovascular events, as the warnings for the entire JAK-inhibitor class state. Reimbursement and availability in Poland depend on current decisions — it is worth asking at a dermatology clinic.

For many people the loss of hair, eyebrows or eyelashes means a loss of sense of identity, fear of being judged and withdrawal from contact. The S3 guideline explicitly recommends that all patients be informed about hair replacement and cosmetic options (for example wigs, hair-thickening products, eyebrow make-up) and psychosocial support. Asking a psychologist for help is not a sign of weakness — with persistently low mood or anxiety it is part of treatment. We write about the link between chronic stress and health in the entry on chronic stress.

Equally often repeated is the view that alopecia areata results from nutritional deficiencies. Deficiencies (iron, vitamin D) may coexist and are worth correcting, but they do not explain the disease, and their correction is rarely enough for regrowth. Studies on ferritin, which we discuss in a separate article on ferritin and hair loss, also show this soberly.

Alopecia areata is a disease that for years had few effective options, and today — at least in severe forms — drugs based on an understanding of the mechanism are available. At the same time many people with milder disease have a good prognosis, and topical treatment and observation are a reasonable strategy. The most important things are not to treat yourself with preparations that lack evidence, to exclude coexisting diseases (especially of the thyroid), to look after mental health and to talk to a dermatologist about realistic goals. Hair regrowth is important, but it is not the only measure of treatment success: well-being and quality of life are equally important.