What wavelengths of low-level laser therapy (LLLT) or photobiomodulation (PBM) are most effective for promoting scalp hair growth?

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Last updated: March 20, 2025View editorial policy

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From the Research

Low-level laser therapy (LLLT) with a wavelength of 655 nm has been shown to be effective in promoting scalp hair growth, particularly when used in combination with 2% minoxidil. This is based on a recent study published in 2024, which found that the combination of 655 nm LLLT and 2% minoxidil resulted in a significant increase in mean hair diameter compared to 2% minoxidil alone 1.

Key Findings

  • The study used a randomized, parallel, controlled, single-blind clinical trial design to evaluate the effectiveness of 655 nm LLLT in combination with 2% minoxidil for female pattern hair loss (FPHL) 1.
  • The results showed that the combination group had a statistically significant increase in mean hair diameter compared to the 2% minoxidil group 1.
  • Another study published in 2021 found that LLLT with a wavelength of 650 nm was effective in downregulating scalp inflammatory biomarkers and boosting the hair regrowth activity of minoxidil 2% 2.
  • A study published in 2021 also found that combination therapy of LLLT and 5% minoxidil was more effective than LLLT or minoxidil alone in improving hair density and diameter in female pattern hair loss patients 3.

Treatment Recommendations

  • For optimal results, use devices specifically designed for hair growth that emit light in the 630-670 nm range, with treatment sessions typically lasting 10-20 minutes, 3-4 times per week for at least 3-6 months.
  • Consider combining LLLT with other treatments like minoxidil or finasteride, but consult with a dermatologist before beginning any combination treatment.
  • Consistency is key for seeing noticeable improvements in hair density and thickness.

Safety and Efficacy

  • LLLT is generally safe with minimal side effects, but it is essential to follow the recommended treatment protocol and consult with a dermatologist before starting treatment.
  • The therapy is most effective for androgenetic alopecia (pattern hair loss) and works best when started early in the hair loss process.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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