What is the recommended 308‑nm excimer laser protocol (initial fluence, frequency, dose escalation, treatment duration, adjunctive topical therapy, monitoring, and alternatives) for a patient with stable, non‑segmental vitiligo who has not responded adequately to topical steroids or calcineurin inhibitors?

308-nm Excimer Laser Protocol for Vitiligo

For stable, non-segmental vitiligo unresponsive to topical steroids or calcineurin inhibitors, combine 308-nm excimer laser with topical tacrolimus 0.1% ointment applied twice daily to maximize repigmentation, particularly for UV-sensitive sites (face, neck, trunk). 1

Initial Fluence and Dose Escalation

• Start at 100 mJ/cm² (approximately 1 MED) for all skin types 2
• For Fitzpatrick skin types I-II: repeat the same dose twice before increasing to avoid burns 2
• For Fitzpatrick skin types III-VI: increase dose at each session based on erythematous response to the previous treatment 3
• Increase fluence in a stepwise fashion, withholding treatment if sunburn develops until complete resolution 4
• The initial dose can alternatively be set at 50 mJ/cm² below the 308-nm minimal erythematous dose measured on vitiligo skin 3

Treatment Frequency

Treat three times weekly for optimal speed of repigmentation. 3 While once-weekly and twice-weekly protocols eventually achieve similar repigmentation initiation rates (dependent on total treatment number), three-times-weekly treatment produces:

• Significantly faster onset of repigmentation (P = 0.0336) 3
• Higher mean repigmentation grade at 12 weeks (3.3 vs. 1.7 for once-weekly; P = 0.018) 3
• 62% of lesions showing repigmentation by 6 weeks compared to 8% with once-weekly treatment (P = 0.0134) 3

If three-times-weekly is not feasible, twice-weekly treatment is acceptable, though it requires longer duration to achieve comparable results 5, 3

Treatment Duration and Endpoints

• Continue for maximum 24-30 sessions or until 75% repigmentation is achieved, whichever comes first 2, 5
• Treatment periods exceeding 12 weeks are often necessary for satisfactory clinical repigmentation, particularly with less frequent dosing schedules 3
• Repigmentation persists in most cases over 12 months of follow-up after treatment cessation 3

Adjunctive Topical Therapy

Apply topical tacrolimus 0.1% ointment twice daily to all treated lesions. 1 The British Journal of Dermatology guidelines document that combining excimer laser with tacrolimus produces superior repigmentation compared to excimer laser monotherapy, though the evidence is limited by small study size and lack of tacrolimus-only control arms 1. The combination is particularly effective for UV-sensitive sites but not for areas over bony prominences 1

• Topical tacrolimus requires no laboratory monitoring (CMP, renal function, or drug levels) as systemic absorption is negligible 6
• Stinging is a common side effect but does not require discontinuation 1

Site-Specific Response Rates

UV-sensitive areas (face, neck, trunk) respond dramatically better than UV-resistant areas:

• Face: 71.5% achieve ≥75% repigmentation; 76.2% achieve ≥50% repigmentation 2
• UV-sensitive areas overall: 57.1% achieve ≥75% repigmentation 5
• UV-resistant areas (bony prominences, extremities): only 15.8% achieve ≥75% repigmentation (P = 0.031) 5
• Hands and feet: poorest response with only 20% showing ≥50% repigmentation 2

This treatment should be preferentially offered for facial and truncal lesions, not for acral vitiligo. 5

Monitoring During Treatment

• Assess repigmentation every 4 weeks using standardized photography 7
• Monitor for erythema at each session before dose escalation 3
• Withhold treatment if sunburn develops; resume only after complete resolution 4
• No laboratory monitoring is required 6

Alternative Phototherapy Options

If excimer laser is unavailable or cost-prohibitive:

• Narrowband UVB (NB-UVB) phototherapy is the preferred alternative 1
• The 311-nm Titanium:Sapphire laser shows non-inferior efficacy to 308-nm excimer laser (mean difference -2.862%, 95% CI -6.531% to 0.807%) and can serve as an alternative 7
• Treatment limits: maximum 200 treatments for NB-UVB in skin types I-III (based on psoriasis data; no defined limit for skin types IV-VI) 1

Common Pitfalls and Caveats

• Do not use excimer laser for active or unstable vitiligo. Confirm no new lesions, no Koebner phenomenon, and no lesion extension for at least 12 months before initiating treatment 1, 8
• Avoid treating acral sites (hands, feet) as first-line with excimer laser given the 80% failure rate 2; consider surgical options (autologous epidermal suspension with laser abrasion followed by NB-UVB) for these sites if cosmetically critical 1
• Do not discontinue tacrolimus prematurely; continue throughout the entire laser treatment course 1
• Age, sex, skin type, MED, and duration of vitiligo do not predict treatment response (P = NS for all variables) 5
• Patients with Fitzpatrick skin type III and above show slightly better overall response rates 2