Clinical Trial Comparing Three Wavelengths in Photobiomodulation Therapy for Hair Loss.

Background: Commercial lasers and light combs have limitations such as restricted wavelengths, inconsistent energy delivery, and variable results. While photobiomodulation therapy (PBMT) at 650 nm has been extensively studied for hair growth, research on PBMT at 1550 nm and 14,000 nm (far infrared radiation, FIR) remains limited. Objective: This study aims to evaluate and compare the effectiveness of PBMT, including 650 nm, 1550 nm, and 14,000 nm, in promoting hair growth and improving scalp health. Method: A controlled study with 68 participants (18-60 years old) assigned them to either PBMT 650 nm, 1550 nm, 14,000 nm, or a control group. Treatment lasts 3 months, with maintenance treatments every 4-6 weeks for up to 9 months. Hair density, scalp condition, and loss were assessed at baseline 3, 6, and 9 months. Results: PBMT at 650 nm, 1550 nm, and 14,000 all improved hair growth over 9 months. Hair density increased in the PBMT groups (100→114 hairs/cm 2 , 99→115 hairs/cm 2 , and 101→107 hairs/cm 2 ), while the control group declined (100→98 hairs/cm 2 ). Among the 68 participants, 42 had oily scalps initially. This condition improved in all treatment groups, with oily scalp cases nearly halved in each treatment group. Conclusion: PBMT (650 nm, 1550 nm, and 14,000 nm) effectively promotes hair growth and reduces hair loss. Further research is needed to refine protocols, explore combinations, and extend follow-up periods.