BACKGROUND Photodynamic therapy (PDT) has been used for acne, however, the efficacy and safety need to be determined. OBJECTIVE To assess the effects and safety of PDT for acne using an evidence-based approach. METHODS Randomized controlled trials (RCTs) on the treatment of acne with PDT were identified by searching PubMed, CNKI and the Cochrane Library. RESULTS A total of 14 RCTs involving 492 patients were included. Photosensitizers included aminolevulinic acid (ALA), methylaminolevulinate (MAL), and indole-3-acetic acid (IAA). Light sources included red light, pulsed dye laser (PDL), intense pulsed light (IPL), long-pulsed dye laser (LPDL) and green light. The PDT protocols, including ALA + red light, ALA + PDL, ALA + IPL, MAL + red light, and MAL + LPDL, all showed great efficacy on inflammatory lesions. ALA + red light also had effects on non-inflammatory lesions and sebum secretion. ALA + IPL and IAA + green light significantly decreased sebum secretion. Triple treatment protocols showed great improvement on inflammatory and non-inflammatory lesions. Increasing ALA concentration, ALA incubation time, PDT sessions, dose of light source or using occlusion for photosensitizers, or a combination of other treatments with PDT may achieve greater efficacy. The common side effects of PDT were tolerable and transient. CONCLUSIONS Limited evidence indicates that PDT shows good efficacy in the treatment of acne with acceptable side effects. ALA + red light was shown to be the optimal choice. However, more RCTs are needed to determine the types and concentrations of photosensitizers and light sources, and the duration of light activation and incubation.