Low-level laser therapy

Low-level laser therapy (LLLT), cold laser therapy or photobiomodulation (PBM) is a medical treatment that applies low-level (low-power) lasers or light-emitting diodes (LEDs) to the surface of the body without damaging tissue. Proponents claim that this treatment stimulates healing, relieves pain, and enhances cell function. Sometimes termed as low-level red-light therapy (LLRL), its effects appear to be limited to a specific range of wavelengths. Its effectiveness is under investigation. Several such devices are cleared by the United States Food and Drug Administration (FDA) The therapy may be effective for conditions such as juvenile myopia, rheumatoid arthritis, and oral mucositis.

LLLT makes use of Grotthuss-Draper law, the first law in photochemistry: light must be absorbed by a chemical substance in order for a photochemical reaction to take place. In LLLT that chemical substance is represented by the respiratory enzyme cytochrome c oxidase which is involved in the electron transport chain in mitochondria, which is the generally accepted theory. Administering LLLT below the dose range does not appear to be effective.

Photochemical reactions are well known in biological research.

LLLT has been promoted for use in treatment of musculoskeletal conditions, including:

LLLT appears to be effective for preventing:

Transcranial photobiomodulation or transcranial low level light therapy is limited in neuromodulation due to several reasons:

Insufficient information from clinical trials compares the effectiveness of different types of devices or device parameters (wavelengths, power output, session time, area of actuation).

Veterinary clinics use cold laser devices to treat a wide variety of ailments, from arthritis to wounds, on dogs and cats. Little research has been done on the effects of such treatments on animals. Brennen McKenzie, president of the Evidence-Based Veterinary Medicine Association, stated, "research into cold laser in dogs and cats is sparse and generally low quality. Most studies are small and have minimal or uncertain controls for bias and error". He allowed that some studies show promising results, while concluding that evidence is not sufficient to support routine clinical use.