What Is MLS Laser Therapy and How Does It Work?

MLS laser therapy is a form of photobiomodulation that uses two synchronized near-infrared laser beams at different wavelengths, delivered simultaneously to reduce pain, inflammation, and promote tissue repair. Unlike single-wavelength laser devices, MLS (Multiwave Locked System) combines a pulsed 905-nanometer beam with a continuous 808-nanometer beam, and the synchronization of these two sources is the technology’s defining feature. The approach has accumulated a growing body of research across musculoskeletal pain, neuropathic conditions, and wound care, though the evidence ranges from strong animal studies and promising trials to areas where the science is still catching up to clinical enthusiasm.

Two Wavelengths, One Synchronized Pulse

The core idea behind MLS is that different wavelengths of near-infrared light interact with tissue in different ways, and combining them produces effects that neither achieves alone. The device pairs a 905-nanometer pulsed laser diode, which fires at high peak power in brief bursts, with an 808-nanometer continuous-wave laser diode running at lower power. Both beams are synchronized so they hit the same tissue at precisely coordinated intervals.¹

The 808-nanometer wavelength is thought to have a stronger anti-inflammatory and anti-edema effect, while the 905-nanometer wavelength penetrates deeper into tissue and is associated with pain relief. By locking these two wavelengths together rather than delivering them independently, MLS aims to achieve both effects at once, with the pulsed beam reaching deeper structures and the continuous beam working on superficial and mid-level tissue. The synchronization also prevents the kind of thermal buildup that can occur with continuous high-power lasers, because the pulsed component delivers energy in short bursts with cooling intervals between them.

This matters because one of the longstanding challenges in laser therapy has been the tradeoff between penetration depth and safety. A higher-power laser reaches deeper tissue but risks heating it. A lower-power laser is safe but may not deliver enough energy to structures like joint capsules or deep muscle layers. The dual-wavelength synchronized approach is MLS’s answer to that problem.

What Happens at the Cellular Level

When near-infrared light hits living tissue, it triggers a chain of events inside cells that researchers call photobiomodulation. For years, the leading explanation centered on a mitochondrial enzyme called cytochrome c oxidase. The theory held that near-infrared light knocked loose nitric oxide molecules that were sitting on this enzyme and slowing it down, essentially unclogging the cell’s energy production machinery. That theory is not wrong exactly, but it turns out to be incomplete. Researchers tested cell lines that completely lacked cytochrome c oxidase and found that photobiomodulation still boosted cell proliferation. The cells also showed increased energy production and higher levels of a key metabolic enzyme, suggesting that the light activates cellular metabolism through pathways that do not depend on any single enzyme.²

This finding is worth understanding because it explains why laser therapy seems to affect so many different conditions. If the mechanism relied on just one enzyme in one type of cell, you would expect narrow, specific effects. Instead, the light appears to give cells a metabolic boost through multiple routes, which is why you see research on everything from muscle injuries to nerve damage to wound healing. The cells involved in each of those processes respond to the energy input, even though the downstream outcomes look very different.

On the inflammation side, research using MLS-specific devices has shown that the dual-wavelength treatment can dial down key inflammatory pathways in fibroblasts, the cells responsible for building and repairing connective tissue. When fibroblasts are activated by inflammatory signals, they ramp up enzymes that produce compounds driving pain and swelling. MLS therapy reversed that activation and kept a central inflammatory signaling molecule trapped in the part of the cell where it cannot switch on inflammatory genes.³ In practical terms, this means the treatment does not just mask inflammation the way an ice pack does. It appears to interrupt the inflammatory process at a molecular level.

Evidence for Musculoskeletal Pain

The largest body of evidence for MLS laser therapy comes from musculoskeletal conditions, particularly joint pain and muscle injuries. In patients with knee osteoarthritis, a study comparing different laser protocols found that the MLS laser produced the largest improvement in knee joint function and pain relief when compared to other laser methods tested.⁴ A separate study on chronic knee pain reported significant improvements in pain scores after a course of treatment, though range of motion did not change significantly.⁵

For chronic low back pain, a double-blind placebo-controlled trial found that patients receiving MLS laser therapy reported significantly lower pain than a sham group at follow-up, though the two groups did not differ on broader measures of function and disability.⁶ That distinction between pain reduction and functional improvement is a recurring pattern in the literature. Patients consistently report feeling better, but objective measures of how well they move do not always follow at the same pace. It may be that pain relief enables people to gradually rebuild function through exercise and daily activity rather than the laser directly restoring it.

Animal research on muscle strain injuries offers a window into why the pain relief occurs. In rats with experimentally induced muscle strains, low-level laser therapy at comparable wavelengths improved walking ability and muscle performance within hours after injury. A dose of 3 joules was as effective as a standard anti-inflammatory drug in improving functional outcomes during the acute phase.⁷ A follow-up study went further, directly comparing laser therapy to diclofenac (a widely used anti-inflammatory medication) given both topically and by injection. The laser outperformed both forms of diclofenac on inflammatory markers and walking ability.⁸

Those animal results should be taken with appropriate caution since they do not automatically translate to humans. But they are useful because they let researchers control the injury precisely and measure inflammatory markers directly, which is harder to do in clinical trials. The finding that laser therapy reduced inflammatory enzyme expression more effectively than a conventional drug is noteworthy and aligns with the cellular-level findings described earlier.

Nerve Pain and Neurological Applications

Beyond joints and muscles, MLS therapy has been studied for conditions involving nerve damage. In an animal model of neuropathic pain, MLS treatment controlled pain and prevented nerve damage through three distinct mechanisms: it reduced inflammation by suppressing a key inflammatory enzyme, it preserved or helped restore the protective myelin sheath around damaged nerves, and it protected the central nervous system by boosting a molecule that clears excess stimulatory signals from around nerve cells.⁹ That third mechanism is particularly interesting because it suggests the therapy does not only reduce the sensation of pain but may actually protect nerves from the kind of overexcitation that worsens chronic pain conditions over time.

Bell’s palsy, a condition where one side of the face becomes temporarily paralyzed due to nerve inflammation, has also been tested. A randomized double-blind trial assigned 60 patients with subacute Bell’s palsy into three groups: MLS laser delivered as a scanning technique, MLS laser delivered point-by-point, and a placebo group. All groups received standard facial exercises and massage. Facial recovery was measured at baseline, three weeks, and six weeks.¹⁰ The trial design itself is encouraging because double-blinding is relatively straightforward with laser devices since a sham device can be made to look and feel identical to the real one but deliver no therapeutic energy. This makes laser therapy trials less susceptible to the placebo issues that plague many physical therapy studies.

Wound Healing and the Inflammation Connection

Wound healing is where the anti-inflammatory mechanism of MLS therapy has the clearest practical relevance. Normal wound healing follows a sequence: first inflammation clears debris and fights infection, then new tissue forms, and finally the wound remodels into a scar. Problems arise when the inflammatory phase gets stuck, which happens frequently in chronic wounds like diabetic ulcers. The persistent inflammation keeps destroying new tissue as fast as the body can build it.

The fibroblast research described earlier showed that MLS therapy can break that cycle. By tamping down the inflammatory activation of fibroblasts while also reducing a growth factor involved in abnormal blood vessel formation in inflamed tissue, the treatment helps shift the wound environment from destructive inflammation toward constructive repair.³ This is a cellular-level finding, and the translation to clinical wound care is still being studied, but the logic is straightforward: if you can convince fibroblasts to stop reacting to inflammatory signals, they can get back to their actual job of building new tissue.

What a Typical Treatment Looks Like

If you walk into a clinic offering MLS laser therapy, the experience is notably undramatic. The device looks like a large arm attached to a base unit, with a handpiece that the practitioner positions over the treatment area. You do not feel the laser beam itself. Some people report a mild warming sensation, while others feel nothing at all. There is no pain during treatment, no recovery time afterward, and no need for anesthesia or skin preparation.

A single session typically lasts between 10 and 20 minutes, depending on the size of the treatment area and the condition being addressed. Treatment protocols vary, but most involve sessions two to three times per week over several weeks. The chronic low back pain trial, for instance, used 12 sessions delivered twice weekly.¹¹ Results tend to be cumulative rather than instant. Some patients notice improvement after two or three sessions, while others do not see meaningful changes until the full course is complete. The research also suggests that the timing matters: one study on neuropathic pain found that different treatment protocols activated different biological responses, with some producing fast but short-lived relief and others triggering slower but longer-lasting improvements.⁹

Safety and Known Limitations

MLS laser therapy has a good safety profile compared to many pain treatments. There are no drugs involved, no injections, and the risk of tissue damage at the power levels used is very low. The main absolute contraindication is direct exposure to the eyes, which is why both the patient and practitioner wear wavelength-specific protective goggles during treatment. Pregnancy, active cancer at the treatment site, and certain photosensitivity disorders are standard precautions, though these are largely based on theoretical risk rather than documented adverse events.¹²

The more honest limitation is evidentiary rather than safety-related. While individual trials show positive results, many of them are small. The chronic low back pain trial, for example, is a well-designed double-blind study but with a limited patient population, and while it found significant pain reduction, it did not find differences in functional disability. The knee osteoarthritis study comparing laser methods found MLS superior, but the overall sample sizes in this field tend to be modest. Large-scale multicenter trials and comprehensive meta-analyses that pool data from many MLS-specific studies are still relatively scarce. A systematic review using text-mining approaches confirmed that the evidence supports MLS effectiveness for musculoskeletal pain, neuropathic conditions, and complex wound care, but also highlighted that the field needs more rigorous and larger trials.¹³

Another practical consideration: MLS therapy is often not covered by insurance. Costs vary by provider and region, but a full course of treatment can run several hundred dollars out of pocket. That price tag makes it important for patients to have realistic expectations. The evidence suggests it can reduce pain, sometimes substantially, but it is not a cure-all, and chronic conditions often require ongoing maintenance sessions.

How MLS Differs from Other Laser Therapies

If you have looked into laser therapy before, you have probably encountered terms like “cold laser,” “Class IV laser,” or just “LLLT” (low-level laser therapy). The field is crowded with devices, and the differences are not always obvious from the marketing. MLS sits in a specific niche: it is a Class IV laser, meaning it delivers more total energy than the old Class III “cold lasers” that dominated the field in earlier decades. But unlike many single-wavelength Class IV devices, MLS uses two wavelengths simultaneously and synchronizes them in a proprietary pulse pattern.

This synchronization is not just a marketing distinction. A significant problem in laser therapy research has been inconsistency. Dozens of studies use different wavelengths, power settings, pulse patterns, and doses, making it difficult to compare results across trials. The MLS system standardizes several of these variables by locking the wavelengths and pulse timing together, which at least makes it possible to compare one MLS study to another. Whether the synchronized dual-wavelength approach is genuinely superior to a well-dosed single-wavelength laser is harder to answer definitively. The knee osteoarthritis study that compared methods found MLS produced the largest improvements, but head-to-head comparisons between MLS and other specific high-quality laser devices remain limited.⁴

Surprising Findings and Open Questions

One counterintuitive result from the research involves the lymphatic system. You might expect that a therapy known for reducing swelling would speed up lymphatic flow, since the lymphatic system is responsible for draining excess fluid from tissues. But a recent randomized controlled trial in healthy volunteers found that low-level laser therapy actually reduced the velocity and frequency of lymphatic contractions, rather than increasing them.¹⁴ This does not necessarily mean the therapy harms lymphatic function. The reduction could represent a calming effect on an already healthy system, or the dynamics may differ in inflamed or swollen tissue. But it is a reminder that the biological effects of laser therapy are more complex than simply “switching on” healing processes, and that findings in healthy tissue may not extrapolate directly to injured tissue.

The mechanistic question of how near-infrared light actually communicates with cells also remains partly open. As mentioned earlier, the cytochrome c oxidase theory turned out to be insufficient, and the alternative pathways have not been fully mapped. Researchers know that light absorption leads to increased cellular energy production and metabolic activity, but the precise chain of events between photon absorption and the anti-inflammatory, tissue-repair, and pain-relief outcomes is still being worked out. This is a common situation in medicine: a treatment works, clinicians can see that it works, but the complete molecular explanation lags behind the clinical evidence.

Veterinary Use

MLS laser therapy has gained substantial traction in veterinary medicine, sometimes outpacing its adoption in human clinics. The same systematic review that assessed human applications found that the veterinary evidence base for MLS covers similar territory, with musculoskeletal pain management, wound care, and neuropathic conditions as the primary applications.¹³ Veterinary clinics frequently use MLS for post-surgical recovery, osteoarthritis in aging dogs, and wound management in animals that cannot tolerate oral anti-inflammatory medications. The appeal is similar to the human case: a noninvasive treatment that reduces pain without the gastrointestinal and organ risks associated with long-term use of anti-inflammatory drugs. For animals that resist taking pills or experience side effects from them, laser therapy offers a practical alternative that requires nothing more than sitting still for a few minutes under the handpiece, which most animals tolerate well.