Early Phototherapy Offers Meaningful Benefit for Certain Patients With Alopecia Areata

Early initiation of phototherapy is most effective for treating alopecia areata (AA), a common autoimmune hair-loss disorder affecting millions worldwide.1

The retrospective study evaluated local and whole-body ultraviolet (UV) phototherapy in 49 patients. Phototherapy initiated within 1 year of symptom onset significantly improved the likelihood of hair regrowth, with comparable results between local and whole-body approaches.

Phototherapy is most effective for alopecia areata when started within 1 year of onset, particularly in older patients and those with multiple-patch or totalis patterns.

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Alopecia areata presents in several clinical subtypes, ranging from patchy hair loss to more extensive forms such as alopecia totalis and universalis. Because its course is unpredictable and treatment responses vary widely,2 identifying which patients benefit from phototherapy has been challenging. Researchers of the new study, published in Photodermatology, Photoimmunology, & Photomedicine, sought to answer that question by examining detailed clinical profiles, laboratory markers, disease severity, and treatment outcomes.

Patients included in the study underwent either local or whole-body UVB or excimer-light phototherapy, with random assignment to irradiation type and device. Treatment intervals followed standardized dosing protocols. Importantly, no systemic immunosuppressants were permitted during the study, allowing researchers to isolate the effects of phototherapy alone.

Disease Duration and Patient Age as Key Predictors

A central aim of the study was to identify which patients responded best, and the clearest predictor identified by the researchers was disease duration. Patients who began phototherapy within 1 year of onset experienced dramatically higher improvement rates, with a mean Severity of Alopecia Tool (SALT) reduction more than triple that of individuals with longer-standing disease (P = .0008). Age also played a role, with patients aged over 40 years showing significantly better outcomes than younger adults, possibly reflecting differences in immune activity or disease chronicity.

Among the patients, more than three-quarters fell into the most severe categories (S4 and S5), with over 75% hair loss at baseline. There was significant clinical diversity among the group, with 31 patients with alopecia universalis, 11 with multiple-patch AA, 4 with totalis, and 2 with ophiasis pattern.

The multiple-patch and totalis subtypes demonstrated the strongest responses, with notably higher SALT30, SALT50, and SALT75 achievement rates compared with universalis or ophiasis.

“The improvement rate in the totalis type may have been better because this classification included acute diffuse and total alopecia of the female scalp, a type with a better prognosis,” noted the researchers.

Across the entire cohort, 53% of patients showed hair regrowth, typically emerging after 20 to 30 treatment sessions. This time-to-response held consistent across AA types, suggesting that treatment duration, rather than subtype, is the key determinant of visible regrowth.

Targeted Irradiation Proves Equally Effective

Surprisingly, treatment modality did not influence success. While whole-body irradiation was initially hypothesized to be superior because of its systemic immunomodulatory effects, the results showed no meaningful differences in improvement rates between local and whole-body phototherapy. The researchers' nearly identical response distributions, both in the overall cohort and specifically among universalis patients, suggest that targeted local irradiation to the scalp may be sufficient to trigger the immunologic shifts necessary for hair regrowth.

Laboratory markers, including eosinophil count, hemoglobin, lactate dehydrogenase, and platelet count, did not distinguish responders from nonresponders. The absence of meaningful biomarker correlations, wrote the researchers, reinforces the idea that timing and disease subtype are more influential predictors than baseline systemic inflammation or hematologic status.

Mechanistically, the authors discussed how UV light may restore the impaired immune privilege of hair follicles by modulating regulatory T cells (Tregs) and reducing Th17-driven inflammation, pathways also supported by prior dermatologic research. While the study did not test mechanistic endpoints, the comparable efficacy of local and whole-body irradiation suggests that follicle-level immune resets may be sufficient to drive recovery.

Only mild, transient side effects were reported, and no blistering or serious side effects occurred, supporting the safety of phototherapy even in severe AA.

References

1. Yamamoto A, Enomoto Y, Sakurai M, et al. Efficacy of local and whole-body phototherapy for the treatment of various types of alopecia areata. Photodermatol, Photoimmunol, Photomed. Published online December 3, 2025. doi:10.1111/phpp.70061

2. Alhanshali L, Buontempo MG, Lo Sicco KI, Shapiro J. Alopecia areata: burden of disease, approach to treatment, and current unmet needs. Clin Cosmet Investig Dermatol. 2023;16:803-820. doi:10.2147/CCID.S376096