Minimal erythema dose variability in Indian skin: clinical implications across pigmentary and inflammatory dermatoses

Minimal erythema dose (MED) testing is a crucial yet underused tool for guiding phototherapy in individuals with darker skin types, where visual erythema is difficult to assess and standard phototyping scales such as Fitzpatrick perform poorly. In this large Indian cohort (n = 270), including 229 patients with vitiligo, we found wide interindividual variability in MED across all diagnoses, with vitiligo showing unexpectedly high MEDs and a weak positive correlation between disease extent and ultraviolet threshold. These findings challenge traditional assumptions about ultraviolet sensitivity and highlight the importance of individualized MED-based protocols in phototherapy, particularly for darker skin types.