High-Intensity Flashlamp Photoepilation: A Clinical, Histological, and Mechanistic Study in Human Skin

OBJECTIVE To examine the clinical, histological, and immunohistological effects of flashlamp photoepilation. DESIGN Nonrandomized control trial with blinded histological study and follow-up of 1 to 20 months. SETTING Private academic practice. SUBJECTS Sixty-seven subjects (10 males and 57 females) with areas of excess body hair. INTERVENTIONS Single (9 subjects) or multiple (58 subjects) treatments (noncoherent, 590-1200 nm, 2.9-3.0 milliseconds, 40-42 J/cm2) to hairy skin. From subjects given a single treatment, biopsy samples were taken immediately after treatment and at different intervals for up to 20 months. MEAN OUTCOME MEASURES Clinical measures include hair counts and morphologic features before and after treatment. Histological measures include terminal-vellus and anagen-other ratios, hair shaft diameter, and morphologic features (routine and immunohistochemical detection of bcl-2, bax, p53, Ki67, cyclin D1, and hsp70) before and after treatment. RESULTS Mean hair loss after photoepilation was 49%, 57%, and 54% for a single treatment and 47%, 56%, and 64% for multiple treatments at follow-up of less than 3 months, 3 to less than 6 months, and 6 months or longer, respectively (P