Types of Hair Loss and Treatment Options, Including the Novel Low-level Light Therapy and its Proposed Mechanism

Mahyar Ghanaat, MD


South Med J. 2010;103(9):917-921. 

In This Article

Low-level Light Therapy

In 2007, low-level light therapy (LLLT) was approved by the FDA as a treatment for hair loss.[23] LLLT is also known as low level laser therapy, red light therapy, cold laser, soft laser, biostimulation, and photobiomodulation.[24–26] Most experts agree that LLLT is safe for the treatment of hair loss, but more studies are needed to confirm its therapeutic effects.[24] LLLT was discovered in the 1960s and first used by the National Aeronautics and Space Administration (NASA) to accelerate wound healing in space.[25] Since then, LLLT has been used to reduce neurogenic pain, reduce inflammation, and promote wound healing.[25–27] Other uses include nonmelanoma skin cancer and its precursors, acne vulgaris, photorejuvenation, hidradenitis suppurativa, and psoriasis.[28] It may also prove helpful in killing bacteria, fungi, and viruses.[28] LLLT has also been used to achieve attenuation of retinal toxicity in methanol-poisoned rats.[27] The role of LLLT in hair growth was discovered accidentally in 1967.[26] In an attempt to test if LLLT causes cancer in shaved mice, researchers discovered that these mice did not develop cancer, but instead grew hair.[26]

Before describing the mechanisms of LLLT, a brief discourse into its terminology will be taken. The term "laser" refers to the fact that monochromatic light is used.[27] This is in contrast to light emitting diode (LED). The term "low level" alludes to the fact there is a specific wavelength of light that has optimal therapeutic effects, and any level higher or lower than this may not be proficient.[26] This therapeutic window ranges roughly from 600 to less than 1,400 nm, and is close to the absorption spectrum of hemoglobin and water, respectively.[26] Furthermore, respiratory chain components (mainly cytochrome c) have a similar absorption spectrum.[26] This low level results in a negligible change in tissue temperature.[25]