We discuss important issues concerning LLLT in our Forum. It also contains editorials and general articles by experts.

Don’t be confused: class 4 lasers are not LLLT!

Class 3 and, for the past few years, class 4 lasers have been available on the laser therapy market. What’s the difference? Which are better?


Low-level laser therapy means light therapy with c o l d, low-energy and coherent light. This light is safe, because it does not heat the tissue. Therefore it belongs to laser class 3B! Here light is discharged in the milliwatt range (up to a maximum of 500 mW).

Yet the term low-level laser therapy is not protected. Some class 4 lasers are also low-energy compared to surgical lasers with a very high power output. They work in a range of up to 30 watt, and their light is w a r m. Therefore they belong to laser class 4, which means they heat tissue and can be dangerous. Thermal effects and skin burns can happen after just a few seconds. Manufacturers of class 4 lasers claim: “Stronger is better. Dangers can be excluded by using specific application techniques.”


We do not claim that 4 lasers have no therapeutic effects! With certain orthopaedic indications and when using suitable application techniques, they can no doubt generate positive results. However, the crucial question is: Do we need them? Are these effects stronger than with traditional low-level lasers so that we should put up with the dangers that class 4 lasers entail? Do they expand the application range and hence offer a genuine advantage?

Our answer is: Definitely not. The contrary is true. We caution against using class 4 lasers in LLLT applications!


Below we compare the two laser classes with respect to their evidence, their safety, and their effectiveness. Moreover, we comment on the claims made by class 4 laser manufacturers.


During the past 40 years, 99% of research on LLLT has been performed with class 3B lasers. There are more than 300 RCTs and over 3,500 scientific studies on the effectiveness of 3B lasers.

Manufacturers of class 4 lasers use the evidence of 3B lasers to promote their products. Hardly any studies are available on the effectiveness of class 4 lasers.


3B lasers are not dangerous, they are safe. Even though a few manufacturers claim the contrary, class 4 lasers are by no means harmless. When applied improperly, they can quickly cause skin burns. Especially in veterinary medicine, in which class 4 lasers are more common, incidents keep happening.

We tested the heating of the tissue by a class 4 laser on a piece of meat (steak).

Irradiating a Steak with a Class 4 Laser
Temperature Comparison Class 3 – Class 4

Depending on the place and purpose of the application, the potential dangers of class 4 lasers are more or less serious. With many applications, it must be advised against using these lasers even if they are applied “properly”. These include, e.g., applications in the area of the eyes and face, on the ear, mucous membranes, open wounds, for nerve regeneration, in the case of dermatological indications, and conditions which involve inflammations.


  • Class 4-thesis: Higher power output = better tissue penetration = more effective
  • 1. Wrong! because:
    The modes of action in LLLT are of a biomodulatory nature and therefore depend primarily on the wavelength!

    Biomodulatory effects are mostly a consequence of the applied wavelength and its absorption coefficient. After all, the purpose of LLLT is to impact the cell’s biochemistry. Different wavelengths have different medium penetration depths in the skin of about 0.3 to 2 mm, which already at a tissue depth of only 6 mm results in penetration differences between 0.000001 and 0.125 mm respectively. This is a factor of 125,000. By contrast, the impact of the power applied is only marginal (e.g., 10,000 for a power difference of 5 mW and 5 W respectively)!
    Due to the critical importance of the wavelength, it is therefore also true that a class 4 laser beam with a wavelength between 940 and 980 nm can penetrate the skin less than a 3B laser with a wavelength between 800 and 900 nm.
  • 2. Wrong! because:
    In LLLT, the depth effect in the tissue is primarily based on amplification effects!
    The depth effect in LLLT is based on the “patient’s internal amplification effects” (PASER according to Mary Dason) which are triggered by LLLT. LLLT does not require very high stimuli, as the primary effects in the cell are set off by very low doses, while high doses have an inhibiting effect. The enhancement and transfer of the effect takes place via potentiating effects along the metabolism paths in the downstream and the intercellular communication paths. This is precisely why LLLT is so effective. In short: The depth effect in traditional LLLT with 3B lasers already exists, and this precisely is LLLT!



  • Class 4 thesis: More is more helpful!
  • 1. Wrong! because:
    Hormesis is a characteristic of biological systems (Arndt-Schulz rule).

    Ever since laser therapy has existed, users have been told about the so-called Arndt-Schulz rule, according to which weak stimuli promote physiological processes, while strong stimuli inhibit them. Clinical experience has confirmed this rule for decades and is well documented, e.g. regarding the treatment of open wounds.
    Even so, the argument that more is better still stands a good chance to sound convincing today. Partly in response to this indestructible notion, which is largely fed by marketing strategies, the University of Massachusetts founded its own association back in 2005: the International Dose Response Society (see Its purpose is to advance the understanding of low-level effects and the associated phenomenon that low doses stimulate while high doses inhibit. Research into biological dose–effect relationships across the entire range from promotion to destruction has great implications for many sciences. These include medical disciplines such as toxicology, pharmacology, neuroscience, immunology, physiology, and radiation biology.
    The research topic is hormesis, from the Greek for “to put in motion, to trigger”. Hormesis refers to the positive reaction of biological systems to exposition of very low stimuli (such as toxins or other stressors). They are also called “eustresses”. Improvement through small doses and inhibition through large doses can be illustrated by an upside-down U-shaped curve. Its shape resembles that of the therapeutic dose window for LLLT, which is based on clinical experience between stimulating and cumulative negative effects due to low doses (mW range) and high doses (W range) respectively.
  • 2. Wrong! because:
    An overdose has negative effects in LLLT.

    Numerous studies tell us that cellular metabolism mechanisms are inhibited by excessive radiation doses. Since the beginnings of laser therapy, inhibitory effects have mostly been ascribed to improper application in the form of overdoses.
    The reason is that in LLLT, the decisive impact factor is not the radiation dose but the wavelength, on which the impact on the cellular metabolism depends almost exclusively. With the right wavelength, it can be achieved with even minimal doses of 0.1 Joule. Stimulation cannot be increased ad infinitum – a physiological system can work no better than perfectly. The physiological limits make sense, and crossing and challenging them may cause great damage.
    Therefore: There exists no evidence for the claim that in LLLT more power means greater effectiveness! There is, however, evidence for the exact opposite! 

    Take a look at the following example:
    Twenty-five RCTs met the inclusion criteria for a systematic review and a meta-analysis on the effectiveness of LLLT in the treatment of tendinopathies conducted in 2010 (Tumilty et al. – Of these 25 studies, 12 had positive and 13 had negative results. The researchers were able to demonstrate that the positive results were related to the fact that the therapeutic dose windows were maintained (that is to say, the doses recommended for LLLT) while the negative studies could be attributed to overdoses.
    Leading authorities on the research of the relationship between dose and effect in LLLT and the greatest experts on LLLT literature, such as Prof. Jan Bjordal, Dr. Jan Tunér and James Caroll, have tirelessly explored these questions for years: How much laser is enough? And how much is too much? How did negative study results come about? And they never stop repeating:
    Yes! There is a dose window in LLLT, and heeding it is crucial for its future and its acceptance!
  • 3. Wrong! because:
    Thermal effects are no primary effects of LLLT.

     There are studies which demonstrate that changes in the redox state of the cell may also be triggered by photothermal (as opposed to photobiomodulatory) effects, which might explain some therapeutic effects of class 4 lasers. According to this explanation, 3B lasers trigger photobiomodulatory processes, and class 4 lasers, photothermal effects. Yet in the latter case, the transition between positive effects that are induced via helpful thermal mechanisms in the cell and inhibiting effects that are a result of overheating are extremely vague. In specific cases, the tipping point depends on so many parameters (such as type, tonus, and physiological age = stress elasticity of the tissue) that it is difficult to conceive how it might be precisely calculated.
    By contrast, photobiomodulatory effects generate only minimal thermal effects due to the cellular stimulation of the metabolism and within the natural physiological margin.

Reliable doses

Manufacturers of class 4 lasers claim that dangers due to overdoses and skin burns are excluded because

  • the laser beam is expanded (i.e., not focused) and applied from a distance (which entails a great loss of intensity) and because
  • the laser beam is constantly moved, so that no excessive intensity can be generated at any one place.

Theoretically, this is true: a class 4 laser is to be handled in such a way that it becomes like a class 3 laser. The great expansion of the beam, treatment from a distance, and constant movement of the laser are to neutralize the dangers class 4 entails while maintaining the alleged advantages that are a result of the greater power (in particular greater tissue penetration). How is that supposed to be possible?
On the one hand the greater power is supposedly more effective (which, as we have seen, is already a basic misconception), and on the other, it is neutralized from the start by the way in which it is to be handled so as to avoid dangers. In plain English: it’s a self-contradictory panacea.
Fact is that when a class 4 laser is applied conscientiously, the same results may be expected as with class 3B lasers – at best.
Conscientious application means: you know precisely the distance from which to radiate, the degree by which the focus has to be expanded, and the movement technique and speed that must be applied to remain within the dose window that is effective with LLLT, and hence to avoid both overdose and underdose. For when using this method, underdosing is by no means impossible: by expanding the beam and moving it further away reduces the beam density to such a degree that it is doubtful if the same energy densities in the tissue can be achieved as with 3B lasers.
Assuming that all adjustment measures for class 4 lasers could be defined so precisely that a 3B laser could be simulated, these settings would certainly have to be fixed. This would be possible with the help of fixed scanners whose effective speed of movement and effective distance to the tissue are ensured. Yet this is impossible with a handheld laser unit.

Laser class Class 3B Class 4
Evidence Very high


Please note: The evidence in LLLT literature was generated with 3B lasers 

It does  n o t  apply to class 4 lasers!

Safety Very high Danger of skin burns


Penetration depth









• Radiation penetration:
Comparable for the same wavelength, as the depth effect of LLLT in the tissue depends primarily on the wavelength rather than the power.

• Depth effectiveness:
The depth effect in the tissue depends on the body’s own amplification effects.



Maintaining the dose window leads to positive results.


• Radiation penetration:
Zero evidence in the entire literature about class 4 laser light penetrating deeper into the tissue.

• Depth effectiveness:
Potentially equally effective in deeper tissue layers, but danger of overdosing in the process.



Overdose and underdose are almost impossible to calculate.

Cost-effectiveness   The fibre-optic cables used with laser class 4 are considerably more expensive than those of class 3 lasers and have a tendency to break.





















  • Class 4 lasers are not lasers in the context of LLLT in the sense in which the term has been used in science and actual practice for 50 years.
  • Class 4 lasers are potentially dangerous without offering advantages either regarding penetration depth in the tissue or regarding depth effectiveness.
  • Class 4 lasers might be able to achieve similar results in certain instances in the treatment of orthopaedic diseases. However, the results are difficult to calculate. So are therefore the contrary effects due to overdoses and underdoses.

Even though smart and clever marketing tries to convince you of the contrary:


LLLT – Making Its Way towards Conventional Medicine – Part 1

LLLT – Making Its Way towards Conventional Medicine

Clinical research on the effects of LLLT is guided by the standard scientific methods for studies in human medicine. A large number of high-quality meta analyses and RCTs exist for the application of pain therapy and wound treatment. Following the standards of evidence-based medicine, they show that LLLT is highly effective.

Moreover, we now have several studies on the modes of action of photobiomodulation at a molecular and cellular level.
Many medical experts, however, are still unfamiliar with photomedicine, and they barely take note of the state of research in the field.

State of research

Clinical research

Today the available literature about the modes of action of LLLT and its effects with all different kinds of indications comprises several hundred studies in the Pubmed database. While the quality of the methods applied in LLLT studies was often poor in the last century, the majority of publications has been guided by scientific standards since then. An evaluation of the literature (reviews, meta analyses) has been conducted repeatedly for specific fields of application.

Consequently, today there exists considerable evidence for specific indications for which the pain-relieving and anti-inflammatory effect of LLLT has been documented in patients with musculoskeletal ailments – such as neck pain, epicondylitides, arthritides, and tendinopathies – suffering from acute and chronic pain. Also, there are a large number of individual studies on all kinds of clinical pictures which often describe a benefit, but due to the usually small number of cases examined they cannot make reliable statements about their statistical significance.

Generally speaking, great effort is still required for a comprehensive evaluation of the extant literature.

Our research archive contains literature (mostly abstracts) on the most important fields of application of LLLT.


Evidence for the effectiveness of LLLT in wound healing processes and pain in the musculoskeletal system

We document studies for two crucial claims of LLLT: the promotion of wound healing and pain relief.

We document studies for two crucial claims of LLLT: the promotion of wound healing and pain relief. Guided by a basic requirement of a minimum number of various quality criteria, we selected two meta analyses (2004) and seven randomized controlled trials (2009–2012) concerning wound healing as well as six meta analyses (2004–2012) and eleven RCTs (2009–2012) concerning pain relief..

We have found highly significant therapeutic effects for both forms of treatment:

  • LLLT can promote and accelerate wound healing when wound healing processes are impaired.
  • LLLT can reduce the intensity and the duration of pain in the musculoskeletal system.

As for the promotion of wound healing, the best results were found in cases of chronic wounds when wound healing was impaired. In the case of wounds that were exposed to permanent pressure (e.g. decubitus ulcers) the success was considerably smaller.

The best results for pain relief were found in cases involving pain in the musculoskeletal system. Accordingly, indications such as neck pain, tendinopathies, epicondylitides, osteoarthritis of the knee as well as temporomandibular dysfunctions are main fields of application of LLLT.

In our research archive you will find studies and scientific articles on these areas of application in the sections Promotion of wound healing and Pain relief

  • Modes of action of LLLT
    The mechanisms of photobiomodulation at the intracellular level has only begun to be understood during the past few years. Until recently, there were no conclusive explanations for how light that is so weak that it does not even lead to a rise in tissue temperature to speak of is supposed to be able to have an impact on inflammations, infections, oedemas, or the healing process of chronic wounds.
    Of late, in vitro and animal studies in particular have described the primary effects triggered inside the cell by low-level lasers in ever greater detail.

  • Anti-inflammatory effects
    Low-level laser light with a fixed wavelength and sufficient energy density has an anti-inflammatory effect by reducing “oxidative stress”, such as raised concentrations of ROS (reactive oxygen species). ROS are intermediate products of cellular respiration and include free radicals and other oxidizing agents. They can alter the molecular structure of proteins and damage the lipid layers of the cell membrane. ROS are also formed by cells of the immune system to fight bacteria and viruses. In very low concentrations, however, they assume a physiological function and are important, for example, as signal transmitters in the brain and in insulin transduction cascades.
    Mitochondria in damaged or ischemic tissue produce nitrogen oxide (NO), which competes with oxygen for bonding with cytochrome c oxidase (COX), the enzyme complex IV of the respiratory chain. Cytochrome c oxidase is a key enzyme for the entire metabolism. It can absorb laser light, which uncouples nitrogen oxide from cytochrome c oxidase (COX). This process is called photodissociation and can relieve impaired mitochondrial respiration due to excessive NO-bonding. Subsequently the synthesis of ATP increases. Thanks to the cascade of the dependent metabolic downstream effects, this results in a reduction of inflammation mediators, such as prostaglandin E2 (PGE 2), interleukin –1 beta (IL1B) and the tumour necrosis factor alpha (TNF alpha). Moreover, anti-apoptotic effects are induced by the inhibition of pro-inflammatory signals through LLLT.

  • Pain-relieving effects
    LLLT can inhibit the fast axon transport in special nociceptors in fibres with a small diameter, and thus obstruct the transmission of pain. In the beginning, the rise of the neural sensitivity threshold to pressure pain is reversible. Repeated treatments lead to a reduction of the sensitivity of the pain neurons in the spinal cord. The accumulation of enkephalins and dynorphins inhibits the formation of the neurotransmitter substance P and thus the peripheral and central transfer of stimuli.
    Moreover, LLLT slows down the degranulation of mast cells, and thus the release of vasoactive amines and inflammation mediators. The promotion of ATP synthesis in the pain receptor strengthens its hyperpolarisation capacity. The sensitivity threshold may rise by up to 50% as a consequence. Opioid peptides (enkephalins, endorphins, and dynorphins) may accumulate in the little-myelinated nerve fibres for the stimulus transfer and also diminish the release of central neurotransmitters in the midbrain (central pain relief).

  • Effects on tissue regeneration and wound healing
    During wound-healing phase I (inflammatory and necrotic phase) LLLT promotes antiphlogistic and anti-oedematous processes. In wound-healing phases II (proliferation phase) and III (epithelialisation) LLLT boosts the oxygen supply of the cell and the proliferation rate of the fibroblasts for the increased formation of collagen and elastin. In wound-healing phase III it moreover promotes the fusion of the cellular lipid bilayers for greater tensile strength of the tissue and stabilizes remodelling.
    What is more, LLLT promotes macrophage activity in the injured area and the regeneration of peripheral nerves following injuries (accelerated formation of the axon’s myelin sheath)

Please check our research archive for research work on the modes of action of LLLT.

LLLT – Making Its Way towards Conventional Medicine – Part 2

LLLT-specific research handicaps

There is a huge discrepancy between clinical studies that supply plenty of evidence and analyses which attest only minor effects to LLLT. Paradoxically, in the case of LLLT it is the vast number of studies that has caused great confusion.

The attempt to analyze scientific studies on LLLT by applying a standardized method contains various difficulties and harbours the danger of distorting the effects. The reason lies in the LLLT-specific tremendous variability of study designs, radiation doses, and of the indications examined in the extant scientific literature on LLLT.

Variable modes of interventio

Studies with various modes of intervention are difficult to compare with one another. The laser-specific treatment parameters and the therapeutic techniques of LLLT vary widely:

laser therapy is applied (1) with different laser units, (2) in different dosages, (3) with different application techniques, (4) with different weightings (as sole measure or add-on therapy), and (5) with varying total numbers of treatments and different treatment intervals.

The complexity of the variables complicates standardization.

  1. Different laser units
    Laser systems use different wavelengths and output powers. There are HeNe (helium-neon), GaAs (gallium-arsenide) and GaAlAs (gallium-aluminum-arsenide), which can also be combined in one device. Their effectiveness tends to vary depending on the field of application. In the 1990s laser units had an output power of 1–5 mW; higher outputs of up to 30 mW were very rare. Today laser devices have considerably higher power outputs of up to 500 mW or even more. For this reason studies on LLLT belong to different “laser generations” whose results can hardly be compared with one another.
  2. Different dosages
    The percentage of studies in the scientific literature on LLLT for which laser units with relatively low output power were used is large. Only in the past ten years have laser units with an output power that was higher by a factor of 100 been used and evaluated. The effectiveness of LLLT for the different indications depends in varying degrees on the power density applied. Higher effective power densities may have an inhibitory effect (such as during certain phases of wound healing) or may also be decisive for an effect to occur (for example in painful inflammations of large joints). Another cause of flawed study results may be over- and underdosing.
  3. Different application techniques
    Laser therapy can be applied “automatically” using “scanners” or tripods – or via handheld laser instruments that allow for direct contact with the skin and make the therapy considerably more effective.
    Laser devices can be used for local radiation (e.g. joints, damaged skin areas, etc.) or to stimulate trigger, pain, and/or acupuncture points and other reflex areas. The lasers can be directed at surface tissue areas (e.g. scratch wounds) or deeper layers of the body (e.g. transmastoid radiation of the inner ear). Moreover, laser therapy can be employed invasively (intravenous, interstitial, and intra-articular laser therapy). Often different treatment methods are combined with one another.
  4. Different weightings
    The type of intervention with LLLT also reflects its specific therapeutic weighting in different clinical pictures.
    In many cases LLLT is not compared with any intervention (placebo). In some meaningful clinical studies, LLLT is compared with established interventions based on conventional medicine. In other words, LLLT is not tested in comparison with an intervention (placebo), but the effects of LLLT are compared with those of a standard medical therapy method.
    Some studies examine the effects of LLLT as add-on therapy to a standard intervention. In these instances the standard intervention (e.g. wound therapy according to the guidelines) plus the co-intervention (simultaneous therapy) with LLLT is compared with the standard intervention performed by itself. In the case of serious, chronic wounds or conditions of great pain, LLLT does not make any “non-inferiority claim”, for instance in comparison with the standard therapies according to the guidelines. In these instances it only claims to be a highly effective add-on therapy to the standard therapy, providing an added benefit – for instance, accelerating and triggering wound healing (endpoint: length of time to wound closure) and/or providing significant additional pain relief (endpoint: e.g. VAS).
  5. Different numbers and frequencies of treatments
    The total number of treatments necessary to achieve a therapeutic effect with LLLT may vary greatly depending on the indication. For example, a single treatment of a superficial skin wound may already have a noticeable effect. By contrast, chronic wounds typically require several treatments to achieve a noticeable and visible effect, and the therapy should be maintained over an extended period.
    Treatment intervals may be adequate or inadequate, too. When dealing with acute ailments, or at the beginning of a treatment, a treatment frequency of 1x/week, e.g., is usually insufficient, while it may suffice when treating chronic ailments.
    In actual practice, the number of and intervals between treatments are adjusted to the individual situation. They depend on how well the individual ailment responds to the treatment. Yet in a clinical study, the necessity to adhere to a standardized intervention protocol makes this individualization impossible.
LLLT – Making Its Way towards Conventional Medicine – Part 3

Flawed studies – wrong dosages

A key parameter for effective laser therapy is the dosage. Especially when treating pain, an effective minimum dose is crucial. The minimum dose is the dose at which a therapeutic effect can just be demonstrated. It varies depending on the indication and can be relatively low (e.g. 3–4 J for a herpes wound on the lip) or very high (e.g. 20 J for alveolitis).

One result of some meta analyses in the field of pain therapy with LLLT around the turn of the century was that many studies which failed to show any proof of effectiveness allowed the conclusion that this was attributable to insufficient dosages. The dependency of the effectiveness on the dosage in LLLT is highly significant.

Even so, studies with a negative proof of effectiveness whose lack of evidence can be attributed to underdosages are still quoted or included in reviews.

Conclusions and the recommendations of WALT

Experts in photomedicine see the decisive reason why LLLT still enjoys such poor acceptance among medical professionals in frequently flawed study protocols. Even though the variability of the study parameters regarding LLLT is very complex, it is possible to deduce precise indication-oriented application protocols for adequate dosages, application technique, and length of application from RCTs on LLLT with positive evidence. In their overview on the state of science in laser photomedicine (The New Laser Therapy Handbook, Prima Books 2010, ISBN 13-978-91-976478-2-3, p. 580) Jan Tunér (board member of the World Association of Laser Therapy, WALT) and Lars Hode (president of the Swedish Laser-Medical Society) state that “ironically, the most significant flaw of many studies on laser therapy is actually the fact that no attention was paid to the therapy method itself.” They are convinced that an improvement of the study designs and precise documentation of all LLLT-specific variables that are employed in a study will lead to the same acceptance of laser therapy which laser surgery enjoys today.

On its homepage, the World Association for Laser Therapy (WALT) offers instructions and recommendations for the purpose of helping scientists and doctors conceive and conduct clinical studies on LLLT.

Further handicaps

The poor response of conventional medicine to the progress in photomedicine is also a consequence of its incorrect placement. What is popular, easy to apply without any risk, and helps with many ailments, is often regarded with scepticism, and it is assumed that there is only little to back it up. The following idiosyncrasies of LLLT are doubtless unusual for many practitioners of conventional medicine:

  • Great range of applications
    LLLT can be applied for many different conditions. Since it acts on primary cellular control centres, it can have an impact on many different kinds of ailments. Being suspicious of “all-rounders” is justified.
    For example, it may be difficult to accept at first that low-level lasers arfe supposed to be helpful for such different clinical pictures as arthritides of the knee, zoster (both are quite well-researched indications of LLLT) and even allergic rhinitides.
    Even if the healing processes which LLLT triggers can be transferred to many clinical pictures, statements about its effect should not be generalized. They can only be made based on clinical studies for clearly defined indications with precise endpoints.
  • Modes of action at the border of quantum mechanics
    Yet another reason is the complexity of the primary, local reactions at a molecular and cellular level which is triggered by LLL radiation. The way light can influence biochemical cell processes is not part of a medical professional’s academic standard knowledge.
  • Application in complementary medicine
    The application of low-level lasers is widespread in complementary medicine. Here it is frequently part of the therapy range of “natural medicine”, which also includes such controversial methods as homeopathy. Scientific statements of evidence regarding the effectiveness of therapy methods are often not as important in this field.
    In fact, the use of low-level lasers in complementary medicine is as old as the invention of laser light. Here lasers serve not only as an alternative source of stimulation – as, for example, in laser acupuncture – but has also established new, original therapy techniques. Frequency-modulated ear acupuncture according to Nogier or Bahr, for instance, can hardly be performed without a low-level laser system.
    The status low-level laser light enjoys in non-evidence-based natural medicine rubs off and also makes things more difficult for those photomedicine experts who are exclusively devoted to researching the direct effects of photobiomodulation.
  • No risks
    When applied properly (e.g. with eye protection), laser therapy harbours no risks and only rarely has slight, fleeting side effects, and in these cases they are almost always a result of overdosage. We are used to the most potent remedies and therapies having frequent side effects. For this reason many people find it hard to believe that the laser photo therapy can have such significant positive effects.
    The absence of risk makes laser therapy “non-elitist”, too. After detailed training that is designed to address their specific ailments, patients can even apply it themselves! This potential has been a major handicap for respectable laser therapy as well, as it also makes the market for ineffective, cheap fake lasers large.
  • Pseudo laser instruments
    It is not least widespread frivolous practices in the marketing of pseudo laser devices that have been devastating for scientific photomedicine. Laser medicine is a business, and light-emitting pseudo instruments are easy to assemble. In this manner instruments are sold as laser units which contain no lasers but only LEDs or even simple light bulbs. Or laser diodes are mixed with LEDs without the therapist typically even being aware of it. Plus, cheap so-called “laser units” for domestic use are advertised in paramedical publications. Most of these cheapo versions do not even carry a CE symbol, and most people do not realize that even CE labelling constitutes no seal of quality (in the sense that the promised effect has been proven) but is an administrative symbol for the purpose of documenting adherence to the legal minimum requirements. The inferior cheap “laser units” usually resemble slide pointers – and their effects are accordingly meagre or entirely nonexistent.
  • Lack of basic know-how
    When applied properly, laser therapy contains no risks – but this does not mean it can be applied without some basic knowledge in order to be effective.Improper application and lack of knowledge about correct dosages – in other words, inadequate preparation in general – often lead to fuzzy, watered-down, and poor results. This is not only true for the everyday practice of physicians. Laser and treatment parameters which are crucial for the success of a therapy are not infrequently poorly documented even in some studies, or reflect a lack of understanding of their significance.Training towards a successful application of laser therapy is not regulated. The manufacturers still bear the main responsibility in this regard. Only respectable manufacturers do not shy away from the effort of making sure that their laser systems are applied properly, and keep their therapists up to date by offering training and information services.
Evidence in biomedical science

What can be said about the quality of biomedical research in general?
Does it live up to its own quality standards?

In a current series of articles (2014) the leading medical journal The Lancet voices harsh criticism of the quality of published evidence in biomedical research. It claims that too much rubbish is produced. As early as 2009, The Lancet had published a paper which maintained that more than 80% of all research investments (in terms of effort and money) was misplaced. Research planning and execution, it argued, were for the most part flawed (e.g. due to inadequate study designs) and negative results were withheld or distorted. This time critical scientists writing in The Lancet criticize the research system as being by and large pitiful.

They hold that some of the responsibility for the poor quality of studies lies with many professional journals, which they believe are overly guided by a desire for sensation and profit, as well as with academic career requirements that demand as many publications as possible within a very short time.

Research rubbish is produced by the following factors, among others:

  • Prior to the study planning, the current status of already existing studies is poorly researched. The result is redundant research.
  • The research topic is irrelevant.
  • When insights from baseline research are actually applied, much of the data cannot be reproduced (for example, researchers of the pharmacological company Amgen were unable to reproduce the data of 47 out of 53 university baseline studies on an important medical issue).
  • Negative data is often not published. About half of all preclinical and clinical studies are not printed.
  • In many studies the study design and the notes on the application are insufficiently defined.
  • Many study results are not publicly accessible.

The authors of the current series of articles in The Lancet make some recommendations as to how these defects can be removed. These concern the application of basic rules of legitimate research that are not new but must apparently be brought to mind once again, and urgently to boot.

A comment on the series of articles by The Lancet authors S. Kleinert and R. Horton (“How should medical science change?”) as well as the articles of the series are available here.


In this context The Lancet website also reminds visitors of Randy Schekman, who in December 2013 received the Nobel Prize for Medicine jointly with James Rothman and Thomas Südhof for their discovery of cellular machineries regulating vesicle traffic. Shekman had seized the opportunity to launch a fierce attack on the “luxury journals” Nature, Science, and Cell.

Expert forum on the laser therapy literature
Annals of Laser Therapy Research

The Annals of Laser Therapy Research provides expert analysis, commentary and discussion of the laser therapy literature.

Damned issue: The laser dose