"Does laser therapy get very hot? Can it burn?" "How is the laser elsewhere different from yours?" These are the questions we are asked most often at the clinic.
The word "laser" makes many people think of cosmetic hair removal or surgical cutting, but therapeutic lasers for pain work in a completely different way: they do not cut the skin or cause burns, but use light energy to switch on the body's own repair mechanisms. Even so, devices that are all called "laser therapy" can differ a great deal. This article explains, step by step, how wavelength, power and temperature control affect treatment, so you can choose with more confidence.
What Is Laser Therapy? Starting With Photobiomodulation
In medicine, using light energy to regulate cell function is called photobiomodulation (PBM). When near-infrared light reaches tissue, it is absorbed by the mitochondria, the parts of the cell that produce energy. This boosts production of the energy molecule ATP and triggers a chain of responses:
- Pain relief: it temporarily slows the speed at which pain nerves send signals, so pain decreases.
- Regulating inflammation: it reduces local inflammatory substances, helping swelling go down.
- Better circulation: it promotes local blood and lymph flow, bringing nutrients to strained tissue.
- Supporting repair: it provides energy for the repair of tendons, muscles and nerve cells.
The whole process is non-invasive, with no injections or medication. Patients usually feel only warmth and can carry on as normal afterwards.
Different Wavelengths, Different Effects
Wavelength is measured in nanometres (nm) and determines which tissues absorb the light and how deep it can go. Lasers for pain mainly use the following wavelengths:
650 nm red light: surface repair
Red light is readily absorbed by melanin and haemoglobin in the skin, so it acts mainly on the skin and shallow tissue, and is often used for wound care and surface problems.
810 nm: the "workhorse" of cell energy
810 nm lies close to the range where mitochondria absorb light best, and is regarded as the main wavelength for boosting cell energy and reducing inflammation. Experiments also show that under the same conditions, 810 nm heats tissue the least, so it feels less hot.
980 nm: warmth and circulation
980 nm is more readily absorbed by water in tissue and produces a noticeable warmth, helping tight muscles relax and boosting local circulation. A 2023 experiment comparing several wavelengths found that 980 nm produced the most heat, so it needs a moving probe or pulsed mode to avoid overheating.
1064 nm: going deeper
1064 nm is less absorbed and scattered by melanin. A systematic review found that it penetrated more deeply in many comparisons and is also more suitable for people with darker skin, making it well suited to deeper tendons, the joint capsule and the deep muscles of the lower back.
What Is the Difference Between Two- and Three-Wavelength Lasers?
Common two-wavelength lasers usually combine 810 nm and 980 nm, covering both cell energy and warmth and circulation. Three-wavelength lasers add 1064 nm (some models use 650 nm red light as the third wavelength), delivered at the same time through one probe, so a single treatment covers tissues from the surface to deep layers.
| Two-wavelength laser | Three-wavelength laser | |
|---|---|---|
| Common combination | 810 nm + 980 nm | 810 nm + 980 nm + 1064 nm |
| Main effects | Cell energy, warmth and circulation | Cell energy, warmth and circulation, plus deep penetration |
| Best suited to | Most muscle and fascia problems | Deeper or larger problem areas, such as the deep lower back and around joints |
| Feeling of heat | Depends on the share of 980 nm; warmth is more noticeable | The mix can be adjusted as needed, balancing depth and comfort |
*Configurations differ between brands and models; the above describes the general picture.
In research, an Italian team treated chronic low back pain with high-intensity laser and compared 650 nm, 810 nm and a three-wavelength 810/980/1064 nm combination: all three groups improved clearly in pain and function, and the improvement was still there at four-month follow-up. Another study of shoulder tendinopathy compared single-wavelength 1064 nm with a four-wavelength combination: both were effective, with a trend towards better pain relief in the multi-wavelength group.
These studies carry an important message: the value of multiple wavelengths lies in "more complete coverage", but more wavelengths do not automatically mean better results. What really determines the outcome is whether enough of the right energy reaches the area that needs treatment.
Why Are New-Generation Lasers Better Than Before?
Early low-level lasers (Class 3B) mostly had a power below 0.5 watts. They worked well for shallow problems but often fell short for deep areas such as the lower back and knees. The reason is simple: research has found that over 90% of near-infrared light energy is absorbed within the first ten millimetres of the body, so if the starting energy is too low, the dose reaching deep layers will be too small.
- Higher power: high-intensity lasers (Class 4) can deliver several to dozens of watts, sending enough energy to deep tissue in a reasonable time.
- Simultaneous wavelengths: different wavelengths work at the same time, with no need to switch between devices.
- Pulse and temperature control: high peak energy is released in pulses while preventing heat from building up, making treatment more comfortable and safer.
- Dose calculation: the total energy (in joules) is set according to the treatment area, tissue depth and skin tone, so each course has a clear basis and is easy to adjust at follow-up.
A 2026 systematic review and meta-analysis of 105 clinical studies of high-intensity laser therapy, covering the knee, spine, shoulder and arm, found a clear reduction in pain that was maintained at follow-up of three months or more. In all 13 direct comparisons, high-intensity laser gave better pain relief than low-level laser, and no serious adverse effects were reported. Another meta-analysis in 2023 also found that high-intensity laser reduces musculoskeletal pain and improves function, most clearly in the knee and shoulder.
What to know before laser therapy
- Safety goggles are essential: therapeutic lasers can damage the eyes, so patients and clinicians must wear special goggles throughout.
- What it feels like: most people feel only warmth; if it feels too hot, tell the clinician straight away so it can be adjusted.
- Tell us beforehand: if you are pregnant, have a tumour, take light-sensitising medication or have a tattoo in the treatment area, say so before treatment.
- Operated by trained staff: the dose of high-intensity laser must be set after an assessment; buying a home device to treat deep pain yourself is not advisable.
Who Is Laser Therapy Suitable For?
Laser therapy is commonly used in the following situations, and is especially suitable for patients who want to take fewer painkillers or would rather avoid injections:
- Long-term back pain, morning stiffness and pain when turning after sitting (see laser therapy for morning back stiffness and tendon knots)
- Tight neck and shoulders, knots and tendon strain, such as tennis elbow, mummy wrist and plantar fasciitis
- Pain and stiffness from knee osteoarthritis
- Numbness and tingling from compressed nerves (see how laser therapy works for nerve pain)
Frequently Asked Questions
Does laser therapy hurt? Can it burn the skin?
Therapeutic lasers do not cut or burn tissue, and most people only feel warmth. High-intensity lasers use a moving probe, pulsed modes and temperature control to stop heat building up; if it feels too hot, the clinician adjusts it straight away.
Which is better, a two-wavelength or a three-wavelength laser?
Each has its uses. A three-wavelength laser adds a wavelength such as 1064 nm, covering more tissue layers, which suits deeper or larger problem areas. But results ultimately depend on an accurate assessment and the right dose, not just the number of wavelengths.
What is the difference between high-intensity and low-level lasers?
Low-level lasers usually have a power below 0.5 watts and suit shallow problems. High-intensity lasers can deliver several watts or more, sending enough energy to deep tissues such as the lower back and joints in a shorter time. When studies compare them directly, high-intensity lasers generally give better pain relief.
How many laser sessions are usually needed?
It depends on the nature of the problem and how long you have had it; clinical studies mostly use courses of a few to a dozen or more sessions. Ever-Health recommends the number of sessions after an assessment and adjusts according to the changes after each treatment.
Who should not have laser therapy?
It should not be applied to the abdomen or lower back during pregnancy, over a tumour, or around the eyes. People taking light-sensitising medication or with a special medical history should discuss it with a clinician first.
Choosing Laser Therapy Is About More Than the Machine
Wavelength, power and temperature control determine what a laser "can do", while an accurate assessment and the right dose determine whether treatment "can help you". If long-term pain is troubling you, book an assessment to find out whether laser therapy is right for you.