Ruby laser-assisted hair removal reduces the coarseness of regrowing hairs: fallacy or fact?

There have been anecdotal reports that hairs that regrow after ruby laser-a ssisted hair removal are finer in appearance. If true, this phenomenon adds to the improved aesthetic effect of laser treatment of unwanted hair. It is the aim of this study to determine whether this phenomenon indeed occ urs, and if so, assess its permanence and its mode of action. In this prospective clinical study, 71 patients with 94 treatment sites wer e treated with the Chromes 694 Depilation Ruby Laser. Hair diameter was mea sured pre-treatment, and at 3 and 7 months post-treatment. In addition, ex vivo scalp skin was used to assess if the ruby laser selectively damaged co arser hairs. Laser-treated and matched untreated skin samples were histolog ically assessed and the diameters of hair shafts (normal or obviously damag ed) were measured. Results of this study were analysed using Kruskal-Wallis one-way analysis. There was no statistically significant difference between the hair diameter of non-lasered specimens and the hair diameter of the normal hair in laser ed specimens. However, a statistically significant difference was seen betw een the hair diameter of non-lasered specimens and diameters of damaged hai r in lasered specimens (P < 0.05). There was a statistically significant di fference (P < 0.05) between pre-treatment and 3 month hair diameters, but n o statistically significant difference was found between pre-treatment and 7 month hair diameters. In conclusion, ruby laser-assisted hair removal results in a temporary redu ction in hair diameter of regrowing hair. This is not due to the selective targeting of larger hair follicles.