Optimal tattoo removal in a single laser session based on the method of repeated exposures

Background Unwanted tattoos are treated with Q-switched lasers. Despite a series of treatments, efficacy is limited. Objective We compared a single Q-switched laser treatment pass with 4 treatment passes separated by 20 minutes. Methods Eighteen tattoos on 12 adults were divided in half and randomized. One half received a single treatment pass (the “conventional” method) with a Q-switched alexandrite laser (5.5 J/cm2 , 755 nm, 100-nanosecond pulse duration, 3-mm spot size), and the other half received 4 treatment passes with an interval of 20 minutes between passes (the “R20” method). Tattoo lightening was compared 3 months later, by blinded evaluation of photographs. Biopsy specimens obtained before and immediately after treatment on both halves were also compared in blinded fashion. Results Immediate whitening reaction occurred on the first treatment pass, with little or no whitening on subsequent passes. Three months later, treatment with the R20 method was much more effective than conventional single-pass laser treatment ( P