Efficacy of 1064nm LP-Nd Yag laser verses 755nm Alexandrite laser for axillary hair reduction in skin of color: A prospective comparison study

Laser hair reduction (LHR) is a popular cosmetic dermatology procedure utilizing several types of lasers along with non-laser intense pulse light (IPL) epilators.2 LHR being a slow process, requires at least six to eight sessions and spaced depending on the hair cycle of the target area for satisfactory results.The principle behind effectiveness of LHR systems is extended theory of selective photothermolysis.1 Specific wavelengths of 600 to 1100 nm target the melanin in the hair follicle and converts it into heat, thermal damage to the stem cells in the hair bulge inhibits future hair regrowth. With repeated sessions, hair regrowth becomes sparser and finer, extending the duration of hair-free intervals.

Different laser systems offer a range of wavelength, from the 694-nm Ruby laser, to the 755-nm Alexandrite (Alex) laser, 800- 810nm Diode and the 1064-nm Nd: YAG laser, with IPL devices covering a broad spectrum from 515 to 1200 nm1. The Nd-Yag was the first laser for epilation to receive FDA approval. Each system’s efficacy and safety vary across different skin and hair types. The Nd- yag laser (1064) stands out for its efficacy and safety particularly for darker skin types (Fitzpatrick skin types IV - VI), due to its deeper penetration and reduced melanin absorption, minimizing epidermal damage6.

However, the Nd:YAG laser has lower melanin absorption limiting its effectiveness on finer and lighter colored hair, potentially requiring more sessions to achieve the desired outcomes6. Conversely, the 755nm alexandrite is very good at targeting melanin in hair follicles particularly is effective for lighter skin types. It offers balance of safety, comfort, effectiveness of long term hair reduction. However, it necessitates a careful understanding for use in darker skin types to minimize adverse effects, given its higher melanin affinity.5

Axillary hair is dark and terminal and requires laser with maximum melanin absorption for effective hair reduction which can be done with alexandrite laser 1 but for skin of color with more epidermal melanin LP-Nd Yag with minimal melanin absorption is safe1.

To the best of our knowledge no studies specifically analyze their efficacy in the dark skin types. Thus, this study aims to address this gap by evaluating the effectiveness and safety of the LP Nd -Yag and Alexandrite lasers in axillary LHR for individuals with skin of color.