The characteristics of erythema induced by topical 5‐aminolaevulinic acid photodynamic therapy

Background: Topical photodynamic therapy (PDT) is increasingly used to treat superficial non-melanoma skin cancers. Knowledge of the characteristics of 5-aminolaevulinic acid (ALA)-induced phototoxicity will increase our understanding of PDT and may facilitate optimisation of treatment regimes. Methods: We examined the characteristics of ALA-induced erythema in 10 healthy subjects and investigated the effect of light source and body site. Results and Conclusion: Maximal erythema occurred within 1–2 h of PDT and inter-individual variation in ALA-induced phototoxicity was seen. No detectable differences were seen in the phototoxicity on back or leg sites or between coherent and non-coherent light sources. These data provide further information to allow us to optimise topical PDT regimes.