Zhang J, et al. - Since photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) was described as an effective treatment for severe acne, researchers compared the effectiveness and safety of PDT with 5% ALA vs 10% ALA in severe acne. On the left or right side of the face, 23 patients with severe facial acne were randomly assigned to receive PDT with 5% ALA or 10% ALA. During the week-4 and week-12 follow-up visits, the decrease rates of lesion counts between the two groups were compared. Except in the first treatment session, no significant difference was noted in pain scores between the two groups. For severe acne, photodynamic treatment with 10% ALA was more efficient than PDT with 5% ALA.