The role of number of treatments in laser-assisted hair removal using a 755-nm alexandrite laser.
BACKGROUND: It is generally accepted that multiple laser treatments yield more effective clinical results; however, it is not clearly known whether increasing the number of treatments would affect the incidence of adverse effect. The main objective of the study was to assess the role of the number of treatments in the efficacy and safety of laser-assisted hair removal in a relatively dark-skinned population. METHODS: A retrospective study of 313 consecutive laser-assisted hair removal treatments was conducted on a total of 23 patients (22 women, 1 man) with 58 anatomic areas by means of an alexandrite laser. Skin types of III and IV were represented. The long-pulsed alexandrite system (Aphrodite, Quanta system, Italy) was used at a 755-nm wavelength to deliver fluences ranging from 17 to 25 j/cm2 through a 10 mm spot size. The patients were divided into 4 groups according to the number of treatments (group I < or =4, group II = 5, group III = 6, and group IV > or =7 treatments). Digital photographs of the patients were used for hair counting. Adverse effects (hyperpigmentation, hypopigmentation, blister, folliculitis) were questioned. The treatment was defined as successful if there was more than 50% hair reduction and an absence of the adverse effects. RESULTS: There was a positive correlation between hair reduction and number of treatments (r = .402, p < .005). The following side effects were observed: hyperpigmentation (two patients, both in group IV); hypopigmentation (one patient in group IV) and blister (one patient in group IV); folliculitis (two patients in group III and IV). Treatment was successful in 48.3% (28 out of 58) of the treatment sites. The success rate was 25% for < or =4 treatments, and 76%, 58%, and 15% for 5, 6, and > or =7 treatments respectively (p = .002). CONCLUSION: Patients who undergo more treatment sessions achieve a higher rate of hair reduction; although this may be concomitant with an increase in the incidence of adverse effects. The benefit of more laser treatments should be balanced with the risk of occurrence of side effects in each patient.