Higher Initial Dosing in Excimer Laser Therapy Yields Faster Vitiligo Repigmentation with Fewer Sessions

A retrospective study from investigators at Nagoya City University Hospital suggests that a minimal blistering dose (MBD)-based excimer laser protocol may produce faster and greater repigmentation in patients with vitiligo compared with a conventional excimer laser approach, without a statistically significant increase in cumulative irradiation dose.¹

Comparing Conventional and MBD Protocols

Excimer laser therapy is already an established treatment option for vitiligo, but the optimal dosing strategy still remains uncertain. Conventional treatment protocols typically begin at half the minimal erythema dose (MED) and gradually increase based on patient tolerance. In contrast, the newer MBD protocol intentionally uses higher irradiation levels designed to induce blistering responses in treated lesions.²

To compare the 2 approaches, investigators retrospectively analyzed outcomes in 43 patients with vitiligo who completed more than 20 excimer laser treatment sessions. Twenty-nine patients received the conventional protocol, while 14 underwent the MBD protocol. Patients selected their treatment approach after receiving counseling regarding both methods and the potential for blister formation with MBD therapy.

In the conventional treatment group, therapy was initiated at one-half of the patient’s MED and increased incrementally until mild erythema persisted for several days. In the MBD group, treatment began at twice the MED, generally corresponding to the blistering threshold. Once photohardening reduced erythematous responses, doses were further increased. Treatment efficacy was evaluated using the Vitiligo Area Scoring Index (VASI) at baseline and after the 10th and 20th treatment sessions.

Treatment Efficacy Results

The investigators found that patients treated with the MBD protocol experienced significantly greater improvement in VASI scores after 10 sessions compared with those treated using the conventional protocol. Researchers also evaluated cumulative treatment response by calculating the area under the curve (AUC₀–₂₀) for percentage VASI improvement over the first 20 treatment sessions. The MBD group demonstrated significantly greater cumulative repigmentation than the conventional treatment group.

In addition, Kaplan–Meier analysis showed that patients receiving MBD-based therapy achieved VASI 50, defined as at least 50% improvement in VASI score, significantly earlier than patients treated with the conventional regimen. The study also found that the difference in treatment response remained significant after both the 10th and 20th treatment sessions, suggesting sustained benefit with the MBD strategy.

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Although the MBD protocol used substantially higher maximum irradiation doses than the conventional protocol, the total cumulative excimer laser dose at the end of treatment was not significantly different between groups. Investigators noted that patients in the MBD group required fewer total treatment sessions overall. The average cumulative number of sessions was 29.8 in the MBD group compared with 56.8 in the conventional group.

Safety Findings and Mechanistic Insights

The authors suggested that achieving repigmentation more rapidly with fewer visits could help “reduce the burden of hospital visits for patients and shorten the time to healing, leading to earlier improvement in their quality of life.” They also noted that conventional narrowband UVB phototherapy often requires 25 to 50 sessions over at least 6 months, highlighting the potential practical advantages of faster repigmentation strategies.

Adverse events were generally mild and transient in both groups. In the conventional protocol group, 2 patients experienced erythema with a burning sensation. In the MBD group, 2 patients developed erythema with burning sensation and 1 patient developed erythema with vesicle formation. All adverse events resolved after a temporary interruption in treatment, and no patients discontinued therapy.

Investigators emphasized that further study is needed to refine the MBD-setting process and determine optimal pretreatment measurement approaches. Because MED was measured on the back rather than at each treatment site, actual blistering thresholds may have varied across anatomical regions. Despite these limitations, the findings suggest that MBD-based excimer laser therapy may accelerate repigmentation while potentially reducing the number of treatment sessions required for patients with vitiligo.

References

1. Yamamoto A, Enomoto Y, Sakurai M, et al. Efficacy of Minimal Blistering Dose-Based Versus Conventional Excimer Laser Therapy for Vitiligo. J Dermatol. Published online May 3, 2026. doi:10.1111/1346-8138.70247

2. Noborio R, Nomura Y, Nakamura M, et al. Efficacy of 308-nm excimer laser treatment for refractory vitiligo: a case series of treatment based on the minimal blistering dose. J Eur Acad Dermatol Venereol. 2021;35(4):e287-e289. doi:10.1111/jdv.17047