Alopecia areata, also called circular hair loss, is characterized by clearly defined areas of total hair loss. Typically, these are one or more approximately coin-sized, mostly round or oval bald areas on the scalp. Often one side of the head is affected more than the other. Hair loss can also occur on the face (beard area, eyebrows, eyelashes) and body. The hair follicles are not permanently damaged by Alopecia areata, but the disease is nevertheless long lasting for many affected persons or occurs in ever new attacks.
In severe cases, the bald patches expand, merge and take up larger parts of the scalp. A special form is alopecia ophiasis: Here the hair falls out in the entire temple, ear and neck area. In another special form, Alopecia barbae, only the cheeks and chin of men are affected. In rare extreme cases, the disease can progress to total hair loss in the head area (Alopecia totalis, including eyebrows and eyelashes) or on the entire body (Alopecia universalis). A diffuse special form of Alopecia areata also occurs, here the diagnosis is made difficult by the similarity to other forms of diffuse hair loss.
The skin of the hairless areas looks smooth, normal and healthy, sometimes a certain redness appears. Diagnosis is also sought for very short, broken hairs, the so-called exclamation mark hairs, which appear on the edges of areas with active alopecia areata.
Hair loss in the context of alopecia areata sometimes announces itself by a burning or itching sensation and often progresses very quickly. It usually stops after some time and new hair grows back. Phases of hair loss, regrowth and stabilisation may repeat at shorter or longer intervals; predictions are not possible. Interestingly enough, however, relapses seem to occur more frequently in February and March 
Ultimately, the disease disappears spontaneously at some point in about half of those affected. However, the risk of progression to total alopecia or universal alopecia increases with the extent of hair loss. If the disease has progressed to these stages, the chance of spontaneous healing decreases .
How common is Alopecia areata?
Worldwide, about 2% of people develop alopecia areata during their lifetime . The disease occurs about equally frequently in men and women and basically starts at any age. Those affected are usually otherwise healthy; there is only a certain association of circular hair loss with autoimmune diseases such as allergies, neurodermatitis, asthma or hypothyroidism .
What are the causes of alopecia areata?
Alopecia areata poses even more of a mystery to science than androgenetic alopecia, although most researchers agree that it is a group of at least partially hereditary autoimmune diseases in which the body’s immune system turns against its own anagen-phase hair follicles. Inflammatory cells collect around hair follicles in the anagen phase (under the microscope, biopsied scalps show so-called “swarms” of T lymphocytes around the anagen follicles of the sample ) and attack the follicles until the anagen phase comes to an early conclusion.
Possibly unknown small malfunctions of the dye-producing cells in the follicle, the melanocytes, could be the stimulus for the immune system. The basis of this hypothesis is the fact that white hair is not attacked or is attacked very late in the course of the disease (interestingly, such progressions give the – false – impression that the affected persons have completely turned grey basically “overnight”) .
Can alopecia areata be treated?
Similar to androgenic alopecia, alopecia areata is not a limitation of other physical health and performance. Certain typical associations with health restrictions (metabolic syndrome in androgenetic alopecia, autoimmune spectrum disorders in alopecia areata) are possible in both forms of hair loss, but probably not the rule. On the other hand, the disease, which is little known despite its relative frequency, should not be underestimated as a source of psychological distress.
A causal treatment or cure is not possible. When it comes to the question of whether treatment should be given or not, the specialists take different positions. Some consider the side effects of standard treatment options to be more serious than the expected benefits, given the fairly high probability of spontaneous remissions. Others argue nevertheless for a rapid start of treatment.
If the aim is to wait to see whether spontaneous remission occurs, a zinc supplement is usually prescribed orally. Zinc is a regulator of the immune system.
Treatment with glucocorticoids
The first step in the drug treatment of alopecia areata today is usually with strongly effective locally applied glucocorticoids (cortisone & co., usually mometasone furoate, betamethasone or clobetasol), which suppress the immune reaction and allow the hair follicles to recover. However, there is no guarantee that the inflammation will not flare up again after stopping the medication. Since glucocorticoids cannot be used permanently in any case (this leads to atrophy – thinning – of the skin), many patients eventually give up this treatment.
In addition to glucocorticoid-containing tinctures, creams or foam preparations, there is also the possibility of injecting these active substances under the skin of the affected areas (intralesional injection of glucocorticoids). In this way also deeper skin layers can be reached and the results tend to be better.
Systemic glucocorticoids (prednisolone) and other immunosuppressive drugs can be prescribed for extensive alopecia areata – these tablets can, however, have considerable side effects. In view of the fact that alopecia areata does not threaten health, it must be considered on an individual basis whether the replacement of hairless areas for susceptibility to infection, weight gain, oedema in the legs, swollen face and other unpleasant effects is really perceived as beneficial.
Another currently available option is the so-called topical immunotherapy with contact allergens. Here – so to speak – the devil hair loss is to be driven out with the Beelzebub allergic reaction: A deal which, if it works, many alopecia areata sufferers are happy to enter into. In several studies, on average well over half of the users responded to the therapy. However, in the long term, about 70% of patients relapsed after the treatment was completed .
In topical immunotherapy, a skin-irritating substance is applied to the scalp every week with the aim of producing contact eczema – popularly explained by the fact that this therapeutic approach is intended to “distract” the immune system from attacking the hair follicles. DPCP (diphencyprone) and SQADBE (square acid dibutyl ester) are used primarily – both contact allergens trigger redness of the scalp, which is accompanied by itching, dandruff and swelling of the lymph nodes. These phenomena, which are necessary for the therapeutic effect, vary in severity from individual to individual. It is possible that the allergic reaction may spread beyond the area of application and/or the formation of weeping blisters may occur. In this case, the dose of the active substance must be reduced.
After a dose-finding period of several weeks, the therapy is usually continued for one to one and a half years and finally terminated by “sneaking out”, i.e. by gradually reducing the concentration of the active substance.
An alternative to the treatment with DPCP or SQUADBE, which is carried out weekly in the dermatologist’s practice, is the home application of an ointment with dithranol or cignolin. The substance irritates the scalp and achieves similar hair growth-promoting results as the topical immunotherapy.
In one study, the combination therapy (daily cignolin plus weekly DPCP) showed about twice as good results as the single therapy with DPCP .
Hair transplants for Alopecia areata
In general, hair transplants are not carried out for Alopecia areata – the risk that the transplanted hair follicles will also be attacked by the immune system is high. There are few reports in the medical literature about experimental transplantations of eyebrows and scalp hair in Alopecia areata. In most cases a relapse occurred: the transplanted hairs were lost again after a few years or could only be preserved by regular cortisone injections .
Minoxidil is also used for Alopecia areata. Study results, most of which date from the 1980s, indicate that evening treatment of the scalp with minoxidil (some study authors emphasise the need for airtight covering of the treated areas overnight ) achieves dose-dependent (1 to 5% minoxidil solution) results in milder forms of alopecia areata in at least half of the users  , whereas in total or universal alopecia totalis rather absent or little pronounced effects should be expected. 18] However, cosmetically really acceptable results are achieved only in very few cases, which should make the relatively cumbersome treatment unprofitable for most of those affected. 21] In women, the problem of possibly growing facial hair is added – especially at higher dosages.
In some studies published in the specialist press in recent years, minoxidil has been used in combination with other therapeutic agents in the hope of synergy effects – with varying but never resounding success: Thus together with microneedling, with topical immunotherapy  and following a six-week systemic glucocorticoid treatment with prednisone, where minoxidil stabilised the hair growth achieved by prednisone for a few months well, but not in the long term .
Alopecia areata sufferers know: “Resounding success” can usually not be achieved with any of the known individual therapies. The management of the disease often includes various therapy components – and as such a therapy component, minoxidil still has a firm place in modern dermatology for Alopecia areata .
In the field of alopecia areata, there are quite a number of experimental therapies whose effectiveness and long-term safety cannot yet be conclusively assessed. Many of these experimental therapies involve immunomodulators. These include the systemic treatment with the so-called Janus kinase inhibitors (JAK inhibitors; several clinical trials are currently underway), with interleukins and statins. Therapy with local injections of enriched autologous plasma (platelet-rich plasma  and combination therapy with the immunosuppressor cyclosporin A and glucocorticoids also appear promising .
It is in the nature of things that the possibility to try out experimental therapies is not given in normal dermatological everyday life for patients. Patients undergoing treatment at university clinics sometimes have the chance to participate in clinical trials in which new treatments are tested.