Efficacy and therapeutic reactions of tri-needle-pretreatment combined with painless ALA-PDT for the treatment of moderate-to-severe acne vulgaris: A randomized controlled trial

•Our study confirms that tri-needle-pretreatment can improve the efficacy of conventional ALA-PDT for the treatment in moderate-to-severe acne vulgaris.•The pain score remained significantly lower for our pretreatment protocol (1.21±1.53 points on a 10-point scale) compared to a pain score of 3.78±2.54 for conventional ALA-PDT.•No standard pretreatment was included in conventional ALA-PDT for acne vulgaris. The proposed tri-needle-pretreatment seems promising as a standard pretreatment in the future.