Excimer light 308 nm therapy for alopecia areata resistant to other treatments: a clinical study of three patients

Anais Brasileiros de Dermatologia | Volume 101, Issue 4 | July–August 2026

Daniela Morales Hermosilla, Josefa Catalán Lobo, Rocío González Cobos, Silvia Guerrero Cornejo.

Introduction

Alopecia areata is a common autoimmune, T-Cell mediated disorder that causes sudden, non-scarring hair loss. It occurs when the immune system mistakenly attacks hair follicles, leading to the development of well-defined patches of hair loss, most commonly on the scalp. However, it can also affect the eyebrows, eyelashes, beard, and other areas of the body. The condition can affect people of any age or sex and varies considerably in severity, with some individuals experiencing small, temporary patches while others may develop more extensive or persistent hair loss. Although alopecia areata is not usually physically harmful, it can have a significant psychological and social impact on affected individuals. The exact cause is not fully understood, but genetic susceptibility and environmental triggers are thought to contribute to its development. [1], [2]

Alopecia areata is considered the second most common form of hair loss after androgenetic alopecia (male- and female-pattern hair loss). It affects people of all ages and ethnic backgrounds and can occur in both males and females. Unlike many other forms of hair loss, alopecia areata is directly impacted by complications of the body’s autoimmune system. [1], [2], [3], [4], [5], [6]

Common Treatments

The treatment of alopecia areata depends on the extent of hair loss, the age of the individual, and how long the condition has been present. In mild cases, particularly when only a few small patches are affected, treatment may not be necessary because spontaneous hair regrowth can occur. For individuals requiring treatment, topical or intralesional corticosteroids are commonly used to reduce the immune-mediated inflammation around the hair follicles. [2], [5], [6] Other topical treatments, such as minoxidil, may also be used to support hair regrowth.

For more extensive or persistent alopecia areata, treatment options may include systemic corticosteroids or Janus kinase (JAK) inhibitors, which target pathways involved in the autoimmune response. JAK inhibitors have become an important treatment option for severe alopecia areata, although their use requires medical supervision because of potential adverse effects. Overall, treatment aims to control the autoimmune activity, encourage hair regrowth, and minimise the psychological and social impact of the condition. [1], [2], [3], [6]

Photobiomodulation-based Therapies

Researchers from the University of Chile have investigated excimer lasers as a targeted phototherapy treatment for alopecia areata, particularly for patients with localised or patchy disease. They explored a clinical study of three patients. [8]

The most commonly studied device is the 308-nm excimer laser (Xenon Chloride), which delivers a concentrated beam of ultraviolet B (UVB) radiation directly to the affected areas of skin, rather than exposing the entire body to UV radiation. This subtype of Narrow-Band-UVB (NB-UVB) phototherapy, emits a monochromatic and coherent wavelength. [5], [6]

Unlike conventional NB-UVB phototherapy, it provides deeper penetration and a more localised effect, enabling targeted treatment of difficult-to-reach areas. This translates into fewer sessions, shorter treatment times, and lower cumulative UVB dosage, thereby reducing the risk of adverse effects. [7]

It is considered safe and does not induce systemic adverse effects, with only local events reported, such as erythema, scaling, pruritus, localised hyperpigmentation, and mild pain. [1], [6]

Its effectiveness has not been demonstrated fully in cases of alopecia universalis or totalis, and there is no consensus regarding the most effective protocol for the use of this device or which patients benefit most.

Exciplex® is a portable, hand-held Monochromatic Excimer Light platform that treats autoimmune skin conditions such as Psoriasis, Vitiligo, Alopecia Areata, Mycosis Fungoides & Atopic Dermatitis. Image courtesy of Exciplex®

Clinical Study

Case 1

A 43-year-old woman, diagnosed with AA during the sixth month postpartum, presented with an extensive alopecic patch affecting the coronal, biparietal, and bitemporal regions, with a SALT score of 54 (Fig. 1A). Trichoscopy revealed yellow dots and fine long hairs. After one and a half years of treatment with methotrexate, deflazacort, topical clobetasol, and oral minoxidil, and due to only a partial therapeutic response, 308 nm excimer light was added. She underwent 23 twice-weekly sessions with escalating doses up to 800 mJ, with no adverse effects. She achieved an excellent response, SALT 0, with trichoscopy showing no signs of activity. No recurrence was observed after 6-months of follow-up. [8]

Case 2

A 30-year-old woman with no medical history presented with four months of burning sensation and pruritus of the scalp. A single frontal alopecic plaque was noted; despite intralesional and topical corticosteroids, the alopecia progressed throughout the scalp. The SALT score was calculated at 46 (Fig. 2A). Trichoscopy showed yellow dots, black dots, broken hairs, coudability hairs, and exclamation-mark hairs, consistent with active disease. Histopathology supported the diagnosis of alopecia areata. After four months of treatment with intralesional corticosteroids, clobetasol 0.05%, and topical tacrolimus 0.1% with poor response, intralesional corticosteroids were discontinued, and deflazacort plus excimer light were initiated. After 16 weekly sessions with escalating doses up to 250 mJ, she achieved a SALT score of 0 (Fig. 2B). No adverse effects occurred. She is currently receiving twice-weekly oral corticosteroids and oral minoxidil, without relapse after three months of follow-up. [8]

Case 3

A 12-year-old boy with no medical history and a diagnosis of alopecia totalis was treated with diphencyprone, clobetasol 0.05%, oral deflazacort, and topical minoxidil 5%. He showed a partial response after three years of treatment, with persistent alopecic areas with signs of activity on the occipital, parietal, and temporal regions. Trichoscopy revealed black dots, broken hairs, and exclamation-mark hairs. Due to poor tolerance to intralesional corticosteroids secondary to pain, excimer light was added to the refractory alopecic patches (Fig. 3A). After 16 twice-weekly sessions with escalating doses up to 700 mJ, he showed hair regrowth (Fig. 3B). Although vellus and pigtail hairs were observed, trichoscopy revealed no signs of activity. He experienced erythema lasting longer than 48 hours on two occasions. [8]

Conclusion

Alopecia areata remains a therapeutic challenge because of its highly variable and unpredictable treatment responses. Excimer lasers, however, have demonstrated a favourable safety profile, good tolerability, and no systemic adverse effects. In all three cases presented, hair regrowth was observed, as assessed by SALT scores and trichoscopy, with only minimal adverse events.

Overall, excimer lasers appear to be a promising and safe therapeutic option for patients with refractory Alopecia areata and may serve as a complementary approach alongside other treatment strategies. However, the absence of standardised treatment protocols highlights the need for further studies to establish its optimal therapeutic role, determine appropriate treatment regimens, and evaluate its potential efficacy as a monotherapy.