The use of low-energy laser light to stimulate hair growth (Avci et al., 2014).

Introduction

Low-Level Laser Therapy (LLLT) or “Photobiomodulation” is a technology that uses low-level light energy (red light 630–670 nm or near-infrared 780–850 nm) to stimulate cellular repair processes without generating heat. The application of LLLT in the hair field began with the incidental observation in 1967 that mice treated with laser treatment had “faster hair growth.” This work compiled and reviewed all the scientific evidence up to 2014 on the mechanism and effectiveness of LLLT in the treatment of androgenetic alopecia (AGA).

Mechanism of biological action

The primary target of LLLT is the enzyme cytochrome c oxidase (CCO) within mitochondria, which absorbs energy from light at wavelengths of 600–1100 nm.
Stimulating CCO results in

Increases the production of ATP (adenosine triphosphate), which is the energy source of cells.
Increase blood flow and oxygen to the hair roots.
Stimulates the expression of genes involved in hair growth, such as VEGF, β-catenin, and HGF.
Prolongs the Anagen phase (growth phase) and reduces hair root atrophy (miniaturization).

These mechanisms work together to promote natural hair root recovery and regrowth.

Clinical evidence

This article summarizes evidence from six major clinical trials, including studies by Leavitt et al. (2009) and Jimenez et al. (2014) using the HairMax LaserComb®, which found that:

LLLT was used three times per week for 16–26 weeks. → Increase the average number of hairs +15 to +25 strands/cm².
Effective in both men and women.
Side effects are minor and mild, such as slight itching or warmth of the scalp.
The response is best in patients with mild to moderate hair loss.

Application

LLLT can be used in a variety of contexts, including:

Monotherapy — For those who do not want to use chemical medications.
Combination therapy — such as in combination with Minoxidil or Finasteride to enhance the effect.
Post-transplant Therapy — Helps reduce inflammation and stimulate new hair growth.

safety

No serious side effects were found in any research.
LLLT is a non-thermal, non-invasive, and non-destructive technology.
Medically used light intensity (3–10 mW/cm²) is safe for both skin and pores.

Summary of results

LLLT is a treatment modality with strong mechanistic and clinical evidence support.
It can increase the density and quality of hair in both male and female genetically modified hair loss patients.
Highly safe and can be used for a long time.
Animal studies also suggest that LLLT stimulates hair growth in chemotherapy-induced alopecia (CIA) .

References

Avci, P., Gupta, G. K., Clark, J., Wikonkal, N., & Hamblin, M. R. (2014). Low-level laser (light) therapy (LLLT) for hair regrowth. Lasers in Surgery and Medicine , 46(2), 144–151. https://doi.org/10.1002/lsm.22170

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