Frequently Asked Questions



Here is a compilation of frequently asked questions about Low Level Laser. Please feel free to drop us an email on the following email ID should you require our inputs to specific queries that are not listed on this F.A.Q. page.





Q: How do therapeutic lasers work?
A: Therapeutic medical lasers heal tissue ailments by injecting billions of photons of visible and /or invisible laser light deep into tissue structures. Tissue naturally contains protein strands called chromophores and cytochromes located in the mitochrondria of a cell, which have the unique ability to absorb laser light energy and transform it into chemical energy for the cell. This chemical energy is utilized by the tissue to significantly accelerate the healing process and reduce pain in the body naturally.

Q: Is Low Level Therapy (LLLT) scientifically documented?
A: There are thousands of published studies that describe the positive effects of laser therapy. These studies range from studies on individual cell types to in vivo double blind control studies. The areas of study range from wound healing to muscular skeletal conditions and have been conducted on different types of laser devices. Medicine is a very good medical database search engine that can provide abstracts and can sell literature. There are also many books on the subject. One very good text is “Low Level Laser Therapy - Clinical Practice and Scientific Background”, written by Jan Turner & Lars Hode.

Q: How deep into tissue can a laser penetrate?
A: The depth of penetration of laser light depends on many parameters such as the laser’s wavelength, the power, the type of device driver (pulse or continuous wave mode) and lastly the technique used. The higher the wavelength typically, the deeper the penetration; however, with wavelengths greater than 950nm the water in the tissue absorbs light and the depth of penetration is drastically reduced in addition to causing heat. Secondly, devices of greater power can provide better penetration. Thirdly, the peak power of the unit is the most critical factor in providing depth of penetration. Thus, devices which are true pulsed have better penetration versus continuous wave devices because they have greater peak power densities for superior photon concentrations at depth.

*The TLC-1000 series of Therapeutic Medical Lasers can provide a direct penetration of tissue 5 cm into tissue and an indirect penetration up to 10 cm.

Q: What is a Super-Pulsed Laser?
A: A Super Pulsed laser produces a high power level of impulse of light for a very brief duration for each pulse. It is the high power during each pulse that drives the light energy to the target tissue. Higher peak power leads to higher photon density, delivering the highest concentration of photons and providing the deepest tissue penetration.

Q: What is the difference between green light, red light and blue light?
A: The colour of laser light is determined by the wavelength outputted.
# Red light is achieved between 600 – 700mW of energy.
# Green Light is achieved when 500 – 500mW of light energy is exerted.
# Blue light is achieved when 400 – 450mW of energy is outputted.
# Green light and Blue light is almost entirely absorbed by hemoglobin red blood cells.

This means that these colours of light cannot penetrate below the dermis (live skin cells), therefore cannot heal tissue below the dermis. Red light, on the other hand, can penetrate the dermis and therefore heals injuries below the skin surface, in fact up to 4” below the dermis.

Q: Is laser (LLLT) therapy scientifically documented?
A: There are many published articles that describe the effects of laser. These studies range from cellular studies to in vivo double blind cross-over studies. The areas of study are very diverse and have been conducted on different types of laser devices. Medline is a very good medical database search engine that can provide abstracts and can sell literature. There are also books on the subject. One very good text is “Low Level Laser Therapy – Clinical Practice and Scientific Background. Written by David Baxter. There are also other texts available on the subject

Q: What is the relationship between Peak Power and Average Power?
A: Average power is computed by multiplying the device’s peak power by the pulse frequency and the pulse duration. Since continuous wave units are not pulsed, the pulse duration and the pulse frequency are both equal to 1 and thus the unit’s average power. Some manufacturers of continuous wave devices have chopped the output to create a pulsing effect. It is important to note that in continuous wave units with a fixed 50/50 duty cycle that the average power of the laser system is reduced to ½. In a true pulsed laser system, increasing the frequency, increases the number of super pulses and hence, increases the average power output. The peak power of a continuous wave device is typically measured in milliwatts whereas in a true pulsed laser the peak power is measured in watts or thousands of milliwatts.

Q: How do I compute the dosage for a laser treatment?
A: Typically, clinicians calculate the Energy Density (E.D.) in J/cm2 for a specific treatment using the following equation:
E.D. (J/cm2) = (Average Power (Watts) x Time (seconds)) / Surface Area (cm2)
Hence; Time (seconds) = (E.D. (J/cm2) x Surface Area (cm2)) / Average Power (Watts)

The surface area is the beam spot size of the laser device used. Since the beam spot size in true lasers is usually quite small, typical E.D.’s for treatment protocols are in the hundreds of J/cm2. Some manufacturers of weaker power devices will advertise use of E.D’s less than 10 in order to advertise shorter treatment times.

Since many clinicians use the grid technique and direct contact on the skin, the surface area in the above equation should be 1 cm2. This makes calculating treatment time very straightforward. It also becomes evident that devices with higher average powers will take less time to obtain the same density.

Q: What factors should I consider in calculating the appropriate dose?
A: Since laser energy is absorbed by water, hemoglobin and melanin, different people will require different dosages so that the target tissue of interest obtains the desired energy density. The depths of the target will also play a major part in this decision. Since light energy will be absorbed by other tissues that lie between the target tissue and the skin surface, one should increase the dose to obtain the desired dosage at the target site. In order to bio-stimulate the tissue, light must reach the target in a sufficient dose otherwise bio-stimulation will not occur.

Q: Are there any harmful side effects/contraindications?
A: No, although one must never shine the laser directly into the eye. Otherwise, we recommend that laser devices not be used on the abdomen of a pregnant woman, in the presence of photosensitive compounds or directly on any cancerous tissue.

Q: Does it have to be a laser?
A: Some manufactures produce devices with super-luminous diodes instead of true laser diodes because they are much cheaper to produce. Super-luminous diodes produce monochromatic light, but it is not coherent and hence scattered in all directions. Studies have shown that lasers are much more effective because of their superior photon density. The most common application for super-luminous diodes is for superficial wounds and surface dermatological conditions. Since these devices are very low powered, (approximately 5 to 15 mW rated and only 1 mW actual) and much of the energy they deliver is scattered, they will require much longer periods of treatment time. Most importantly, super-luminous diodes because of their low photon density will not be effective at delivering energy to tissues below the dermis.

Q: How do I know which laser I should buy?
A: Here are some tips to help determine which instrument is a good value for your money:

1. “Laser instruments” have been sold which do not even contain a laser, but LEDs and sometimes even ordinary light bulbs. These instruments have been sold for between US $3,000 - $30,000. Ask for proof that the instrument really does contain a laser.

2. In a number of products, laser diodes have been combined with LED’s. This is often not mentioned. Check that all light sources in the apparatus (except guide lights and warning lights) are real lasers.

3. For oral work and wound healing HeNe and GaAIAs are the most common types and GaAIAs as the most versatile. Sterilizable probes are normally only available for GaAIAs lasers. For injuries to joints, vertebrae, the back, and muscles, that is, for the treatment of more deep-lying problems, the GAAs laser is the best documented. For veterinary work, laser designed so that the light can pass through the coat, and penetrate to the desired depth is best. For superficial tendon and muscle attachments, the required depth can be reached with the GaAIAs laser. Many companies have only one type of laser, such as a GaAIAs, and the salesman will naturally tell you that it is the best model for everything, and that it is irrelevant which type of laser is used. However, research tells quite a different story.

4. Size, colour, shape, appearance and price vary a great deal from manufacturer to manufacturer. Because a piece of equipment is large, it does not necessarily follow that its medical efficacy is high, or vice versa. The most important factor is the dosage that enters the tissue. Make sure the laser you buy is designed so that the light actually enters the tissue. Ask the salesman: How is the dosage measured? What kind of dosage is too high, and what is too low?

5. Many companies which import lasers have deficient knowledge in terms of medicine, laser physics, and technology. In fact, there are many examples of companies that have gone bankrupt. If a piece of equipment is faulty, it may have to be sent to the country of manufacture for repair. How long would you be without your equipment in such a case, and what would it cost to repair? Can the importer document his expertise? Who can you speak to who has used the apparatus in question for a long period of time? Is there a well-known professional who uses this make? What does it cost to change the laser diode or laser tube, for example, after the guarantee has expired? Can you get written confirmation of this? Try to get a list of references.

6. The difference between a colourful brochure and reality is often considerable. There are examples of brochures which describe the output ten times that which the equipment actually provides. How can you find out the real performance of the equipment (e.g. its output)? Are the measurement results from an independent authority? Is it possible to borrow an apparatus in order to measure its performance? Is there an intensity meter on the apparatus which can measure what is emitted and show it in figures? It is not enough simply to have a light indicator.

7. Some dealers know that their products are sub-standard. This can often be seen by the fact that they are anxious to get the customer to sign a contract. If a product is good, the dealer will have no doubts about selling it on sale-or-return basis, with written confirmation of this. What happens if the medical effects are not as promised? Is it possible to get a written guarantee of sale-or-return? In most countries, therapy lasers must be approved. The approval certificate shows the laser type and the class to which the instrument belongs, e.g. laser class 3B. There is also a certificate number. A laser which is not approved is either not a laser, or is being sold illegally.

8. Many companies organize courses and “training” events of markedly varying quality. A serious importer or manufacturer takes pains to ensure that his equipment is used in a qualified way, and makes sure that the customer receives some training in its use. What are the instructor’s background and qualifications? Has he or she published anything? Is there a course description? What does the training material cost? Is a training course included in the cost of the equipment? Is the training material included? Is it possible to buy the training material only?

9. Development is going on at a fast pace. Suddenly, you have out-of-date laser equipment and a new and perhaps more efficient type of laser comes onto the market. What happens if your laser becomes outmoded? Do you have to buy a new laser, or can your equipment be updated with future components lasers?

Q: What is the difference between normal light and laser light?
A: The major difference between laser light and normal light is the laser beam’s ability to travel long distances without being dispersed. This is known as coherence, and it enables the laser to focus its power within a small circumference. Pulsated laser light has been shown to have a strong therapeutic effect on cells and muscle tissue. A Theralase cold laser, for instance, doesn't produce heat or cut organic tissue like industrial lasers or surgical lasers. Instead, it pulses a focused or culminated light beam at body tissue (bone, skin, muscle, etc.) which in turn has profound beneficial effects on the functioning of human cells, the building blocks of the body.

Q: How does cold laser help in the treatment of Rheumatoid Arthritis?
A: Rheumatoid Arthritis (RA) is an autoimmune disorder that attacks the joints causing swelling and tissue damage. RA is different than non-inflammatory problems of the joints and often mistaken for Osteoarthritis, which is inflammation caused by wear and tear on the joints.

Cold laser treatment works by reducing the pain and inflammation caused by Rheumatoid Arthritis. The initial treatment schedule can vary dependent upon the severity of the condition and the length of onset, though the average patient will receive 2-3 treatments per week for a duration of 10-25 treatments. Since RA is an autoimmune disorder and is non-curable, in order to maintain quality of life a patient is placed on a maintenance program of one to two treatments per month thereafter to maintain pain reduction, inflammation and increased range of motion.

Q: What is photon dosage?
A: Photon dosage is defined as the amount of light at tissue depth determined by the amount of light delivered to the tissue surface, affected by both power and time.

Q: How do I get better treatment outcomes with deep tissue?
A: The attenuation or diminishment of light through tissue follows a 1/e formula significantly reducing the amount of light at tissue depth. To provide better treatment outcomes a practitioner needs to maximize the amount of photon light at the tissue surface by increasing the power of the laser and time of the treatment. The limiting factor with laser is the amount of light that tissue can absorb non-thermally, this is known as the Maximize Permissible Exposure or MPE. To date, a super-pulsed laser, flickering off and on, delivers the most amount of photonic energy without exceeding the MPE.
Q: Why is cold laser dosage important?
A: Laser irradiation is dose dependent. In a recent clinical study by our clinical researchers 100mW of power with the Theralase TLC-1000 was too much power for a mouse knee joint and only increased the iNOS expression 200%, but 25mW of power, which was more suitable for a mouse knee joint, increased the iNOS expression 700%. This is startling evidence that can now help us further fine tune our laser protocols.

Q: What / why / how laser?
The word "laser" stands for "light amplification by stimulated emission of radiation.

Lasers are possible because of the way light interacts with electrons. Electrons exist at specific energy levels or states characteristic of that particular atom or molecule. The energy levels can be imagined as rings or orbits around a nucleus. Electrons in outer rings are at higher energy levels compared to those in the inner rings. Electrons can be bumped up to higher energy levels by the injection of energy-for example, by a flash of light. When an electron drops from an outer to an inner level, "excess" energy is given off as light.

The wavelength or color of the emitted light is precisely related to the amount of energy released. Depending on the particular lasing material being used, specific wavelengths of light are absorbed (to energize or excite the electrons) and specific wavelengths are emitted (when the electrons fall back to their initial level).

Q: Why use lasers?
Laser surgery systems are very efficient and have well-documented applications, but are extremely expensive and physically take up a great deal of space. This expense adds to the financial burden of both the medical institution carrying out the laser surgery and the patient undergoing it. In almost all cases, the patient must come to where the laser is, due to the aseptic needs associated with surgery and the electrical connection requirements of laser surgical equipment. Well-designed laser therapy systems on the other hand require a normal mains supply. Many LLLT systems offer a fully portable, battery-powered option allowing the laser to be taken where it is needed, easily and simply. This is a boon for trained laser therapists working in rural areas or developing countries. LLLT systems are comparatively inexpensive, but have a wide range of applications, thus helping to bring about a reduction in the never-ending upward spiral of health care costs to both institutions and patients. Although the end result is very often equally good, LLLT has been proved to work more quickly and at an earlier stage than conventional surgery or therapy, thus, amongst other advantages, dramatically reducing bed time in acute injuries, the period of incapacitation in ambulatory patients, and analgesic requirements post-surgery. All of these point to potential savings for institutions and better health care for patients at lower costs. The reports in the literature on the clinical applications of LLLT all agree that laser therapy, in appropriate situations and delivered by fully-trained professionals, is efficient and safe. Although the systems are still lasers and must therefore be used safely and by trained therapists, laser therapy is totally noninvasive. It can additionally be applied interstitially in certain cases, or through flexible endoscopes to reach the articular aspects of affected joints. LLLT is usually painless, and in more than 35 years of application has been serious side-effect free. LLLT is well-tolerated by all ages and conditions of patients and in a large variety of specialties from neurosurgery and dentistry to podiatry. As each year passes, more and more applications are being presented in which LLLT is not only appropriate, but is better than conventional methods. Hand in hand with the clinical reports, advances in scientific research are elucidating the pathways and mechanisms by which laser therapy works, thereby firmly establishing LLLT as the medical tool of tomorrow, but available today.

A therapeutic laser system is athermic (no heat), with no appreciable heat transfer to the tissue. (< 0.65 degree Celsius) An athermic laser system, therefore, is not able to cause tissue damage as tissue damage arises only through thermal actions.

Thermic lasers, on the other hand, are used for invasive surgery as they cut, burn or vaporize tissue to achieve tissue removal.

Therapeutic lasers utilise a wavelength of monochromatic light in the 630 to 905 nanometer (nm) range, known as the “therapeutic window”. A wavelength of 905 nm has the least absorption in this “therapeutic window”, due to the primary influence of melanin. In the 630 to 905 nm range, the 905 nm wavelength is absorbed least by the skin and hence provides the greatest penetration of photons into the underlying tissues. It is this principle which creates the ability to “inject” photons of energy harmlessly into tissue, “energising” or “bio stimulating” this tissue into an accelerated rate of healing.

The tissue effect of lasers can best be characterized by understanding the absorption of light in tissue. The three main components of tissue that affect the absorption of light are water, haemoglobin (pigment that renders blood red) and melanin (pigment that gives skin its natural color). The absorption curves for these three substances versus the laser wavelength will determine the precise impact that a particular laser will have on tissue.

The purpose of a low level laser is to stimulate. The lower energy levels and the unfocused light beam do not impart large amounts of energy. They do provide enough energy to excite the mitochondria and cause it to undertake big-chemical reactions.

The mitochondria once stimulated by the application and infusion of light energy, produces enzymes and ATP. Cells communicate and operate using chemical signals - enzymes. Low level laser therapy is safe because cells have a natural ability to resist over-stimulation. It is not possible to harm tissue by overdosing.

Serotonin is a neurotransmitter that is used as a marker chemical for low level laser therapy. A patient who receives this type of therapy will, within 24 hours, test positive for increased serotonin by-products in their urine (Walker, Neuroscience Letters). The amount of 5- hydroxyindoleactic acid, the serotonin byproduct, is disproportionately large in comparison to the amount of energy put into the system by the treatment.

The photoactivation of enzymes used provides a huge amplification factor for initiating a biological response using light energy. (Smith, The Photobiological Basis of LLLT). The measurable effects of LLLT appear in calcium ion channels, RNA and DNA at the cellular level, and the production of proteins, fibroblasts, Iymphocytes and leukocytes (Basford, The Orthopedics Journal).

There is a well-documented inter-cellular communication phenomena of "enzyme cascading." Once cells are stimulated to produce an enzyme with the LLLT laser, the adjacent cells are stimulated by the presence of the newly produced enzymes to also produce the same chemical, effectively duplicating and enlarging the effects of light stimulation.

All of the enzymes produced are those naturally used and produced by the cell. They are produced in the ratios and quantities normally used by the body, and the result is a natural healing process. The major difference between a laser and a powerful normal light is the laser beam’s ability to travel long distances without being dispersed. This is known as coherence, and it enables the laser to focus its power very specifically. This source of light has been shown to have a strong therapeutic effect. The Theralase therapeutic lasers do not produce heat or cut like industrial lasers or powerful surgical lasers. At specific wavelengths, a Theralase laser can have profound beneficial effects on the functioning of human cells – the “building blocks” of all the body systems and body tissue (bone, skin, muscle, etc.)

The energy produced by a Theralase laser can be directed at damaged tissue cells, and by giving the cell a massive energy boost, helps to speed up the healing process. Lasers have been shown to improve the repair of tissues, from injuries such as muscle strains/sprains, ligament and tendon injuries, open wounds and bone injuries including fractures and joint dysfunction.

How does laser light heal?
Every cell in the body has light sensitive chemicals called cytochromes. These chemicals are located in energy compartments in the cell called mitochondria. When you stimulate cytochromes with the correct wavelength and power of light it provides the cell with extra energy to grow, regenerate and heal. This bio-chemical reaction increases the production of Adenosine Triphosphate (ATP) which initiates vasodilation bring more oxygen rich blood to injured area.

Q: What is Laser Therapy?
Lasers have been used in surgery since the early 1960’s following the development of the first successful laser in 1960. Ophthalmology and then dermatology were the first medical specialties to use the intense photon density of the pure beam of laser energy to induce photothermal effects which were capable of welding detached retinae, selectively coagulating small blood vessels on the retina, and removing abnormally coloured cutaneous lesions without damaging surrounding normal tissues. This was the birth of laser surgery.

In 1968 a Hungarian clinician and scientist, Professor Endré Mester, published a paper on a nonsurgical application of laser, the induced healing in weeks of non-healing leg ulcers, some of which had a history of years of unsuccessful conventional therapies. This was the birth of laser therapy.

Laser therapy is the application of low incident levels of laser energy to achieve an ever-increasing number of clinical indications. These include: pain attenuation in a large variety of acute and chronic pain entities including pain related to abnormalities in the nerves, soft tissue, muscles, tendons, joints and bone; improved wound healing in soft tissues, tendons and bone including the induction of healing in slow-to-heal or non-healing wounds; improved local and systemic blood circulation, very useful in blood-related conditions such as Buerger’s and Raynaud’s diseases and torpid leg ulcers; increased lymphatic circulation and drainage which improves the early inflammation and swelling associated with acute injuries; enhanced autoimmune response in immune-deficient conditions such as psoriasis, rheumatoid arthritis and atopic dermatitis; and in more specific indications such as the control of hypertension and the restoration of normal pigment in selected abnormally coloured cutaneous lesions.

Laser therapy is delivered using dedicated systems, designed to produce optimum levels of laser energy at specific wavelengths to achieve the desired therapeutic effect in complete safety. These systems should be compact enough to be easily portable; rugged enough to withstand extended use in and out of the treatment room; and reliable enough to preclude constant technical problems while being easily maintained.

How does a therapeutic laser system work?
Laser therapy has been increasingly used in medicine over the last few years as a non surgical means of effecting cures for a variety of pains and ailments, for assisting normal healing processes to occur earlier and better, and as prophylaxis against the occurrence of undesirable side effects. Let us look concisely at what laser therapy is, how it works, and why it is used.

Light energy consists of small packets of energy, called photons, which travel in a wave-like pattern. The number, or density, of photons in a beam of light energy, combined with the wavelength, or colour, of the light will determine what reaction will occur when the energy is incident on tissue. When incident photon densities are not high enough to cause any rise in tissue temperature, the energy is transferred directly to the target cells, which changes their level of activity. It only takes one photon, in theory, to achieve a photoresponse in a target cell. The wavelength of the laser energy will determine how deeply the beam penetrates: infrared lasers have the best penetration, thus achieving deeper absorption which is of great importance in treating muscle and joint pain types. Depending on the condition of the cells and their surrounding tissue the reaction may be photoactivation, such as induced wound healing, or photo retardation, such as the slowing down of pain transmission to give pain attenuation. These opposite sides of the same therapeutic coin are collectively referred to as photoactivation or photomodulation.

In laser surgery, the level of laser-tissue reaction is higher than the survival threshold of the target cells, and the target cells are damaged or destroyed. In laser therapy, on the other hand, the level of reaction is lower than the survival threshold, and the cells are activated. Thus a common term seen in reports is low level laser therapy, or LLLT. All our tissues consist of cells, and so all tissues are potential targets for laser therapy, from skin to bone. The energized cells communicate with each other, and with non-irradiated cells, through increased levels of intra- and extracellular chemicals. If the cells are in a normal condition, then the level of activity remains higher for a short period, and then drops down to normal. Even in a ‘normal’ patient, an almost immediate flood of endorphins, our body’s naturally-occurring opiate, occurs after laser therapy, but as they are not required for any specific pain control mechanism, they are quickly dispersed throughout the body, and naturally disappear. In other words, laser therapy assists the natural healing processes of the body: if there is a need for these processes, such as in the relief of a painful condition, or repair of damaged tissues, then the normal healing mechanisms occur more efficiently. ‘Normalization’ is the keystone of laser therapy, and so LLLT can be used to remove pain or to cure numbness; to remove abnormal colour from, or restore pigment to depigmented skin; to increase blood flow in blood-starved tissues, or decrease blood flow in certain birthmarks such as ‘strawberry marks’; and to control both hypotension and essential hypertension. Just as some patients do not respond to a particular medication but will respond to a different one, so some patients will not respond to LLLT, or will respond poorly. Similarly, some patients need a combination of medications: thus some patients will need LLLT used in combination with other therapeutic modalities. From a study of the many papers on LLLT published in the international medical literature, we can confidently say in pain attenuation, for example, which is the largest application of LLLT, we can guarantee more than 76% pain relief in over 80% of patients. Laser therapy is not a magic wand!

Q: What is the difference between a Hot Laser and a Cold Laser?
# A Hot Laser is a surgical laser used purposely to cut and/or destroy tissue. This is a class 4 laser
# Cold laser is a therapeutic laser created for tissue healing and does not destroy or damage tissue and does not create heat. We are a class 3B laser.

Q: What is Wavelength?
Wavelength determines the colour of a laser beam. Light energy exceeding 700mW becomes clear or infrared.

Q: What is a Super-Pulsed Laser?
A Super Pulsed laser produces a high power level of impulse of light for a very brief duration for each pulse. It is the high power during each pulse that drives the light energy to the target tissue. Higher peak power leads to higher photon density, delivering the highest concentration of photons and providing the deepest tissue penetration.

Q: What is the difference between green light, red light and blue light?
The colour of laser light is determined by the wavelength outputted.
# Red light is achieved between 600 – 700mW of energy.
# Green Light is achieved when 500 – 500mW of light energy is exerted.
# Blue light is achieved when 400 – 450mW of energy is outputted.
# Green light and Blue light is almost entirely absorbed by hemoglobin red blood cells.

This means that these colours of light cannot penetrate below the dermis (live skin cells), therefore cannot heal tissue below the dermis. Red light, on the other hand, can penetrate the dermis and therefore heals injuries below the skin surface, in fact up to 4” below the dermis.










Low Level Laser Therapy

Theralase, Inc. Canada



Introduction to Laser Therapy


How does it work?






Contra - Indications


Conditions treated


Pain Management


Wound Healing


Arthritic Conditions




Addiction Rehabilitation




Why Theralase LLLT?