RESUMO
BACKGROUND: Photodynamic therapy (PDT) has been shown to be an effective alternative for acne. However, there is little information comparing the efficacy of red light alone and methyl aminolaevulinate (MAL)-PDT. AIMS: To compare the efficacy and tolerability of red light alone and MAL-PDT in patients with mild to moderate facial acne. METHODS: Thirty six patients with mild to moderate acne were enrolled. Eighteen patients recieved MAL-PDT and 18 received red light alone in two sessions, 2 weeks apart. Acne grade and lesion counts were assessed by blinded evaluators at baseline, 2, 4 and 10 weeks. RESULTS: At week 2, clinical improvement from acne grade II-IV to 0-I was observed in 82.3% of MAL-PDT group and 14.2% of red light alone group. Red light alone group had a gradual clinical improvement over time with a 77% response at week 10. In contrast, MAL-PDT group had a rapid clinical improvement with total response at week 10. Both treatments were significantly effective for improving acne lesions. However, MAL-PDT group had a greater response (P < 0.001). Histologically, decreased amounts of sebocytes and lipids along with atrophic sebaceous glands were observed after MAL-PDT. CONCLUSION: MAL-PDT has a quicker onset of action with a higher response than red light alone. MAL-PDT may induce a reduction in the size of the sebaceous glands and then long-term acne remission.