Quantitative assessment of growing hair counts, thickness and colour during and after treatments with a low-fluence, home-device laser: a randomized controlled trial

BACKGROUND:
At-home laser and intense pulsed-light hair removal continues to grow in popularity and availability. A relatively limited body of evidence is available on the course of hair growth during and after low-fluence laser usage.
OBJECTIVES:
To assess growing hair counts, thickness and colour quantitatively during and after cessation of low-fluence laser treatment.
METHODS:
Thirty-six women with skin phototypes I-IV and light to dark-brown axillary hairs were included. Entire axillary regions were randomized to zero or eight self-administered weekly treatments with an 810-nm home-use laser at 5·0-6·4 J cm(-2). Standardized clinical photographs were taken before each treatment and up to 3 months after the final treatment for computer-aided quantification of growing hair counts, thickness and colour.
RESULTS:
Thirty-two women completed the study protocol. During sustained treatment, there was a reduction in growing hair that reached a plateau of up to 59%, while remaining hairs became up to 38% thinner and 5% lighter (P < 0·001). The majority of subjects (77%) reported 'moderately' to 'much less hair' in treated than untreated axilla, and assessed remaining hairs as thinner and lighter (≥ 60%). After treatment cessation, hair growth gradually returned to baseline levels, and 3 months after the final treatment the count and thickness of actively growing hair exceeded pretreatment values by 29% and 7%, respectively (P ≤ 0·04).
CONCLUSIONS:
Sustained usage of low-fluence laser induced a stable reduction of growing hair counts, thickness and colour. The reduction was reversible and hairs regrew beyond baseline values after cessation of usage. Computer-aided image analysis was qualified for quantification of hair counts, thickness and colour after laser epilation.