Low-level laser therapy (LLLT), cold laser therapy, or photobiomodulation (PBM) is a form of

medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practice ...

that applies low-level (low-

power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may ...

)

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The firs ...

s or light-emitting diodes (LEDs) to the surface of the body. Whereas high-power lasers are used in

laser medicine Laser medicine consists in the use of lasers in medical diagnosis, treatments, or therapies, such as laser photodynamic therapy, photorejuvenation, and laser surgery. Lasers Lasers used in medicine include in principle any type of laser, but ...

to cut or destroy tissue, it is claimed that application of low-power lasers relieves pain or stimulates and enhances cell function. The effects appear to be limited to a specified set of wavelengths, and administering LLLT below the dose range does not appear to be effective.

Mechanism

Research is ongoing about the mechanism of LLLT. The effects of LLLT appear to be limited to a specified set of wavelengths of laser, and administering LLLT below the dose range does not appear to be effective.

Photochemical reactions Organic photochemistry encompasses organic reactions that are induced by the action of light. The absorption of ultraviolet light by organic molecules often leads to reactions. In the earliest days, sunlight was employed, while in more modern times ...

are well known in biological research, and LLLT make use of the first law in photochemistry ( Grotthuss-Draper law): 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 An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples thi ...

mitochondria A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...

, which is the generally accepted theory.

Medical uses

Various LLLT devices have been promoted for use in treatment of several musculoskeletal conditions including carpal tunnel syndrome (CTS),

fibromyalgia Fibromyalgia (FM) is a medical condition defined by the presence of chronic widespread pain, fatigue, waking unrefreshed, cognitive symptoms, lower abdominal pain or cramps, and depression. Other symptoms include insomnia and a general hyp ...

osteoarthritis Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the ...

, and

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involv ...

. They have also been promoted for

temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that it ...

disorders,

wound healing Wound healing refers to a living organism's replacement of destroyed or damaged tissue by newly produced tissue. In undamaged skin, the epidermis (surface, epithelial layer) and dermis (deeper, connective layer) form a protective barrier agains ...

smoking cessation Smoking cessation, usually called quitting smoking or stopping smoking, is the process of discontinuing tobacco smoking. Tobacco smoke contains nicotine, which is addictive and can cause dependence. As a result, nicotine withdrawal often make ...

, and

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in w ...

. LLLT appears to be effective for preventing

oral mucositis Mucositis is the painful inflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer. Mucositis can occur anywhere along the gastrointestinal (G ...

in recipients of a

stem cell transplant Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to prod ...

with chemotherapy. In other areas, evidence for LLLT remains conflicted. Some studies suggest that LLLT may be modestly effective, in relieving short-term pain for

, chronic low back pain, acute and chronic neck pain,

tendinopathy Tendinopathy, a type of tendon disorder that results in pain, swelling, and impaired function. The pain is typically worse with movement. It most commonly occurs around the shoulder ( rotator cuff tendinitis, biceps tendinitis), elbow (tennis el ...

, and possibly, chronic joint disorders. The evidence for LLLT being useful in dentistry, and in the treatment of

is unclear.

Veterinary use

Veterinary clinics use cold laser devices to treat a wide variety of ailments, from arthritis to wounds, on dogs and cats. Very little research has been done on the effects of this treatment on animals. Brennen McKenzie, president of the

Evidence-Based Veterinary Medicine Association The Evidence-Based Veterinary Medicine Association (EBVMA) is an international, non-profit (501(c)3) professional organization founded with the mission of better organizing the emerging veterinary research, training, and practice of evidence-based ...

, has stated that "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". While allowing that some studies show promising results, he reports that others do not. While believing that there is enough evidence to warrant further study, he concludes that there is not enough evidence to support routine clinical use of cold laser in animals.

Society and culture

History

Hungarian physician and surgeon

Endre Mester Hungarian physician Endre Mester (1903–1984) was a pioneer of laser medicine, especially the use of low level laser therapy (LLLT). In 1967, only a few years after the first working laser was invented, he started his experiments with the effects ...

(1903-1984) is credited with the discovery of the biological effects of low power lasers, which occurred a few years after the 1960 invention of the

ruby laser A ruby laser is a solid-state laser that uses a synthetic ruby crystal as its gain medium. The first working laser was a ruby laser made by Theodore H. "Ted" Maiman at Hughes Research Laboratories on May 16, 1960. Ruby lasers produce pulses of ...

and the 1961 invention of the helium–neon (HeNe) laser. Mester accidentally discovered that low-level ruby laser light could regrow hair during an attempt to replicate an experiment that showed that such lasers could reduce tumors in mice. The laser he was using was faulty and wasn't so powerful as he thought. It failed to affect the tumors, but he noticed that in the places where he had shaved the mice in order to do the experiments, the hair grew back more quickly on the treated mice than on those among the control group. He published those results in 1967. He went on to show that low level HeNe light could accelerate wound healing in mice. By the 1970s, he was applying low level laser light to treat people with

skin ulcers An ulcer is a sore on the skin or a mucous membrane, accompanied by the disintegration of tissue. Ulcers can result in complete loss of the epidermis and often portions of the dermis and even subcutaneous fat. Ulcers are most common on the skin of ...

. In 1974, he founded the Laser Research Center at the Semmelweis Medical University in

Budapest Budapest (, ; ) is the capital and most populous city of Hungary. It is the ninth-largest city in the European Union by population within city limits and the second-largest city on the Danube river; the city has an estimated population o ...

, and continued working there for the remainder of his life. His sons carried on his work and brought it to the United States. By 1987, companies selling lasers were claiming that they could treat pain, accelerate healing of sports injuries, and treat arthritis, but there was little evidence for this at that time. Mester originally called this approach "laser biostimulation'", but it soon became known as “low-level laser therapy" and with the adaptation of

light emitting diodes A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...

by those studying this approach, it became known as "low-level light therapy", and to resolve confusion around the exact meaning of "low level", the term "photobiomodulation" arose.

Names

Under the medical subject heading Low Level Light Therapy the terms following terms are accepted as alternative terms; LLLT, Laser Biostimulation, Laser Phototherapy, Low-Level Laser Therapy, Low-Power Laser Irradiation, Low-Power Laser Therapy, and Photobiomodulation Therapy. The term Photobiomodulation therapy is considered the preferred term by industry professionals. However LLLT has been marketed and researched under a number of other terms, including red light therapy, low-power laser therapy (LPLT), soft laser therapy, low-intensity laser therapy, low-energy laser therapy, cold laser therapy, bio-stimulation laser therapy, photo-biotherapy, therapeutic laser, and monochromatic infrared light energy (MIRE) therapy.American Cancer Society
Cold Laser Therapy
Page archived April 24, 2015 More specific applications sometimes have their own terms, for example when administered to acupuncture points, the procedure is called laser acupuncture. When applied to the head, LLLT may be known as transcranial photobiomodulation, transcranial near-infrared laser therapy (NILT), or transcranial low level light therapy.

Government Action

The FDA filed a complaint for injunction in 2014, alleging that company QLaser PMA were marketing their devices as being able to treat “over 200 different diseases and disorders,” including cancer, cardiac arrest, deafness, diabetes, HIV/AIDS, macular degeneration, and venereal disease. This case resulted in a permanent injunction against the manufacture, marketing, sale, and distribution of those devices in 2015. In 2017, the owner of QLaser, Robert Lytle, and two of QLaser's distributors were charged with a criminal conspiracy to commit fraud. Lytle pleaded guilty to one count of conspiracy to introduce misbranded medical devices into interstate commerce with the intent to defraud and mislead, and one count of criminal contempt in January 2018. Lytle was sentenced to serve 12 years in prison and made an initial restitution payment of $637,000. Lytle's conspirators were sentenced to 24 months and 15 months, respectively.

Reimbursement

Blue Cross Blue Shield Association Blue Cross Blue Shield Association (BCBS, BCBSA) is a federation, or supraorganization, of, in 2022, 34 independent and locally operated BCBSA companies that provide health insurance in the United States to more than 106 million people. It was f ...

and

Aetna Aetna Inc. () is an American managed health care company that sells traditional and consumer directed health care insurance and related services, such as medical, pharmaceutical, dental, behavioral health, long-term care, and disability plans, ...

provide coverage for the prevention of

, but not any other reason."Infrared therapy"
Aetna clinical policy bulletin 0363, reviewed June 17, 2020. Aetna has additional information in it

The

Centers for Medicare and Medicaid Services The Centers for Medicare & Medicaid Services (CMS), is a federal agency within the United States Department of Health and Human Services (HHS) that administers the Medicare program and works in partnership with state governments to administer M ...

does not provide coverage for LLLT.

&" target="_blank" class="mw-redirect" title=""Decision memo for infrared therapy devices" (CAG00291N)">"Decision memo for infrared therapy devices" (CAG00291N)
Center for Medicare & Medicaid Services, Oct 24, 2006.

Cigna Cigna is an American multinational managed healthcare and insurance company based in Bloomfield, Connecticut. Its insurance subsidiaries are major providers of medical, dental, disability, life and accident insurance and related products and se ...

lists LLLT as "experimental, investigational, or unproven for any indication" and provides literature review summaries for a number of conditions.

Research

Musculoskeletal

Evidence does not support a benefit in delayed-onset muscle soreness. It may be useful for muscle pain and injuries. A 2008

Cochrane Library The Cochrane Library (named after Archie Cochrane) is a collection of databases in medicine and other healthcare specialties provided by Cochrane and other organizations. At its core is the collection of Cochrane Reviews, a database of systema ...

review concluded that LLLT has insufficient evidence for treatment of nonspecific

low back pain Low back pain (LBP) or lumbago is a common disorder involving the muscles, nerves, and bones of the back, in between the lower edge of the ribs and the lower fold of the buttocks. Pain can vary from a dull constant ache to a sudden sharp feel ...

, a finding echoed in a 2010 review of chronic low back pain. A 2015 review found benefit in nonspecific chronic low-back pain. LLLT may be useful in the treatment of both acute and chronic neck pain. In 2013, however, a systematic review and

meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...

of LLLT for neck pain indicated that the benefit was not of significant importance and that the evidence had a high risk of bias. There are tentative data that LLLT is useful in the short-term treatment of

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

caused by

, and possibly chronic joint disorders. A 2019 systematic review and meta-analysis found evidence for pain reduction in

. While it does not appear to improve pain in temporomandibular disorders, it may improve function. There is tentative evidence of benefit in

. A 2014 review found benefit in shoulder tendinopathy. A 2014

Cochrane review Cochrane (previously known as the Cochrane Collaboration) is a British international charitable organisation formed to organise medical research findings to facilitate evidence-based choices about health interventions involving health profess ...

found tentative evidence that it may help in

frozen shoulder Adhesive capsulitis, also known as frozen shoulder, is a condition associated with shoulder pain and stiffness. It is a common shoulder ailment that is marked by pain and a loss of range of motion, particularly in external rotation. There is a ...

Mouth

Similarly, the use of lasers to treat

chronic periodontitis Chronic periodontitis is one of the seven categories of periodontitis as defined by the American Academy of Periodontology 1999 classification system. Chronic periodontitis is a common disease of the oral cavity consisting of chronic inflammation ...

and to speed healing of infections around dental implants is suggested, but there is insufficient evidence to indicate a use superior to traditional practices. There is tentative evidence for dentin hypersensitivity. It does not appear to be useful for orthodontic pain LLLT might be useful for wisdom tooth extraction (complications).

Hair loss

LLLT has been studied as a treatment for

hair loss Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarrin ...

; a review in 2012 found little evidence to support the use of lasers to treat hair loss. A 2014 review found tentative evidence for benefit for lasers, while another 2014 review concluded that the results were mixed, had a high risk of bias, and that its effectiveness was unclear. A 2015 review found tentative evidence of benefit,. Additionally, a 2017 review of clinical trials found 10 of 11 trials reviewed "demonstrated significant improvement of androgenic alopecia in comparison to baseline or controls when treated with LLLT."

Brain injuries

LLLT has been studied for

traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic ...

(TBI) and

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop funct ...

among other conditions. When applied to the head it is known as transcranial photobiomodulation or transcranial low level light therapy.

Cancer treatment side effects

LLLT has been studied as a way to reduce pain and swelling in breast-cancer related lymphedema.

Stem cells

An ongoing area of research is the application of LLLT for increasing cell proliferation, including

stem cells In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type o ...

References

{{Lasers Laser medicine Alternative medicine Bioelectromagnetic-based therapies Light therapy Hungarian inventions