Photobiomodulation therapy (PBM) is a non-invasive treatment that uses specific wavelengths of red or near-infrared light to interact with tissues in the body. It is sometimes referred to as low-level light therapy, low-level laser therapy (LLLT), cold laser therapy, or therapeutic laser therapy.
In physical therapy, photobiomodulation may be used as part of a comprehensive treatment plan to help manage pain, support tissue recovery, and improve a patient's ability to participate in rehabilitation.
But what does the research actually say about photobiomodulation therapy? And is it right for you?
What Is Photobiomodulation Therapy?
Photobiomodulation therapy uses light at specific wavelengths and doses to produce biological effects in cells and tissues. Unlike surgical lasers, therapeutic PBM is designed to produce a biological response without intentionally damaging or ablating tissue.
PBM commonly uses red and near-infrared wavelengths, although the exact wavelength, power, energy, treatment time, and application technique can vary depending on the condition being treated and the device being used.
The goal is not simply to "heat" an area. Instead, researchers believe that light can influence cellular signaling and mitochondrial activity, potentially affecting processes involved in pain, inflammation, and tissue recovery.
How Does Photobiomodulation Work?
One of the most studied theories involves the mitochondria, which are structures inside cells responsible for producing energy.
PBM may interact with cellular photoacceptors, including cytochrome c oxidase, an enzyme involved in the mitochondrial electron transport chain. Research suggests that light exposure may influence mitochondrial signaling and cellular energy production, although the exact mechanisms of PBM are still being investigated.
Researchers have also investigated the role of nitric oxide, reactive oxygen species, calcium signaling, and other cellular pathways in the response to photobiomodulation. These pathways may help explain why PBM can influence inflammation, pain signaling, and tissue responses.
It is important to note that the biological mechanisms of PBM are not completely understood. Some commonly promoted explanations are supported primarily by laboratory or mechanistic research rather than strong clinical trials. Therefore, PBM should be viewed as an evolving area of research rather than a treatment with one universally established mechanism.
What Does Photobiomodulation Feel Like?
PBM is generally considered a non-invasive and well-tolerated treatment.
Depending on the device and treatment settings, patients may feel little to no sensation during treatment. Some devices may produce mild warmth, but therapeutic PBM is not intended to damage tissue.
The treatment itself is typically relatively quick, although the exact duration depends on the area being treated, the device, and the treatment parameters selected by the clinician.
What Conditions Can Photobiomodulation Help With?
Research has investigated PBM for a wide range of conditions. However, the quality and strength of evidence varies considerably depending on the condition.
In physical therapy and rehabilitation, areas of research include:
- Musculoskeletal pain
- Knee osteoarthritis
- Neck and shoulder pain
- Sports-related injuries
- Muscle soreness and recovery
- Tendon-related conditions
- Soft-tissue injuries
- Exercise recovery
- Certain inflammatory conditions
This does not mean that PBM is proven to treat every one of these conditions. The results of clinical studies vary based on the diagnosis, treatment parameters, and study quality.
For example, a 2024 systematic review and meta-analysis published in Physical Therapy examined PBM for knee osteoarthritis. The researchers found that PBM reduced pain compared with placebo, but the certainty of the evidence was rated very low because of limitations and risk of bias among the included studies. The authors concluded that PBM may be useful as a complement to other recommended treatments rather than as a stand-alone treatment.
This distinction is important when considering evidence-based physical therapy.
Can Photobiomodulation Help With Pain?
Pain management is one of the most studied applications of PBM.
Research suggests that PBM may influence biological processes associated with inflammation and pain signaling. Clinical trials have reported improvements in pain for several musculoskeletal conditions, although results are not consistent across all diagnoses.
A 2024 systematic review and meta-analysis examining injured athletes found that PBM may help reduce musculoskeletal pain and potentially support return-to-play outcomes. However, differences between studies in treatment parameters and injury types make it difficult to establish one universal PBM protocol for athletes.
This is why a physical therapist should determine whether PBM makes sense for a particular patient rather than using the same treatment protocol for everyone.
Can Photobiomodulation Help With Muscle Recovery?
PBM has also received attention in sports medicine and performance settings.
Research has investigated whether applying PBM before or after exercise can influence muscle soreness, fatigue, muscle damage, and recovery.
A systematic review and meta-analysis of randomized controlled trials found that PBM may improve certain measures of muscle endurance and recovery. However, results have varied depending on the population, activity level, treatment timing, and PBM parameters.
Other research has been more cautious. A 2023 systematic review with meta-analysis found that PBM may help with fatigue recovery in healthy individuals but did not find convincing evidence that it improves muscle strength or overall functional capacity.
More recent research also suggests that PBM may reduce some measures of exercise-related muscle soreness, but the certainty of evidence remains limited.
The takeaway: PBM may be a useful recovery tool for certain patients and athletes, but it should complement—not replace—strength training, mobility work, appropriate loading, sleep, nutrition, and other components of a well-designed rehabilitation program.
Does Photobiomodulation Help Tendon Injuries?
PBM has been studied for several tendon-related conditions, including Achilles tendinopathy.
However, the evidence is not equally strong for every tendon injury.
For example, a systematic review and meta-analysis examining PBM for Achilles tendinopathy found low to very low certainty evidence and concluded that the available research was insufficient to support routine use of laser therapy as a stand-alone treatment.
This highlights an important principle of evidence-based physical therapy: a treatment can have promising biological effects without necessarily having strong evidence for every diagnosis.
For tendon injuries, rehabilitation typically focuses on appropriately progressed loading and exercise. PBM may be considered as an adjunct when clinically appropriate.
What About Neck and Shoulder Pain?
PBM has also been investigated for neck and shoulder conditions.
A 2024 comprehensive review identified 36 clinical studies examining PBM for shoulder and neck pain and disability. The authors found evidence suggesting potential benefits, while also noting differences between studies and treatment protocols.
Because neck and shoulder pain can have many different causes, treatment should be based on the patient's specific presentation rather than simply applying a laser to the painful area.
A physical therapist may combine PBM with:
- Therapeutic exercise
- Strength training
- Mobility exercises
- Manual therapy
- Neuromuscular re-education
- Postural and movement retraining
- Activity modification
- Sport-specific rehabilitation
Why Do Treatment Parameters Matter?
One of the most important concepts in photobiomodulation research is dosage.
There is not one universal PBM dose that works for every patient.
Important treatment variables include:
- Wavelength
- Power
- Irradiance
- Energy
- Energy density
- Treatment time
- Spot size
- Number of treatment points
- Treatment frequency
- Distance from the tissue
- Location of treatment
The World Association for Photobiomodulation Therapy (WALT) provides condition-specific recommendations and emphasizes the importance of standardized treatment parameters.
Research also suggests that PBM may have a biphasic dose-response, meaning that more light does not automatically mean better results. An insufficient dose may not produce the desired biological response, while an excessive dose may also be less effective.
This is one reason professional application matters.
Is Photobiomodulation the Same as Class IV Laser Therapy?
Not exactly.
Photobiomodulation is the therapeutic concept, while different devices can deliver PBM using different light sources and treatment parameters.
Some physical therapy clinics use Class IV therapeutic lasers to deliver higher-powered light to targeted tissues. Other PBM devices use lower-power lasers or LEDs.
The terms "PBM," "low-level laser therapy," and "therapeutic laser" can overlap in the research literature, but the devices and parameters used in studies are not necessarily interchangeable.
For this reason, the specific device, wavelength, power, and dosage should be considered when interpreting research.
Is Photobiomodulation Safe?
PBM is generally considered a non-invasive and well-tolerated treatment when appropriately applied.
However, "non-invasive" does not mean that treatment is appropriate for everyone or that every device can be used in every situation.
A qualified healthcare professional should determine whether PBM is appropriate based on a patient's medical history, diagnosis, medications, treatment goals, and the specific device being used.
Proper eye protection is also important when required by the laser or light device.
Does Photobiomodulation Replace Physical Therapy?
No.
PBM should generally be viewed as an adjunct to rehabilitation, not a replacement for active physical therapy.
For many musculoskeletal conditions, the foundation of rehabilitation includes progressive exercise, strength development, mobility, motor control, education, and gradual return to normal activities.
PBM may be incorporated when the physical therapist believes it can support the overall treatment plan.
For example, a patient recovering from an injury might receive PBM to help manage symptoms while also performing therapeutic exercises designed to restore strength, mobility, balance, and function.
The goal is not simply to make the painful area feel better. The goal is to help the patient move better and return to the activities that matter to them.
What Does the Research Say Overall?
The evidence surrounding photobiomodulation is promising but condition-specific.
High-quality systematic reviews and meta-analyses have reported potential benefits for certain types of pain, osteoarthritis, muscle recovery, and sports-related applications. At the same time, other studies have found limited or inconsistent effects, and some areas have low or very low certainty evidence.
An umbrella review published in 2024 evaluated systematic reviews of high-intensity laser therapy for musculoskeletal pain. Although many reviews reported reductions in pain, the authors noted that the methodological quality of the systematic reviews varied and that additional high-quality research is needed.
This means PBM should not be presented as a cure-all.
Instead, the current evidence supports a more balanced approach: photobiomodulation may be a useful tool within an individualized rehabilitation program when the patient's condition and the available evidence support its use.
What Should Patients Expect During a PBM Treatment?
Your physical therapist will first evaluate your condition and determine whether PBM is appropriate for your goals.
If it is included in your treatment plan, the clinician will select treatment parameters based on factors such as:
- Your diagnosis and symptoms
- The tissue being treated
- The depth and location of the target area
- The specific device being used
- Available clinical evidence
- Your response to treatment
PBM may then be combined with other physical therapy interventions, such as therapeutic exercise, manual therapy, neuromuscular re-education, mobility training, or sport-specific rehabilitation.
Your response to treatment should also be monitored over time. If a modality is not contributing meaningfully to your progress, your treatment plan can be adjusted.
The Bottom Line
Photobiomodulation therapy is a non-invasive treatment that uses specific wavelengths of red or near-infrared light to influence biological processes within cells and tissues.
Research suggests that PBM may help with certain types of pain, inflammation, muscle recovery, and musculoskeletal conditions. However, the strength of evidence varies significantly by diagnosis, and treatment parameters can greatly influence outcomes.
For patients, the most important takeaway is that PBM should not be viewed as a replacement for active rehabilitation. Instead, it can be considered one tool within a comprehensive physical therapy program.
At Core Performance Physical Therapy, modalities such as therapeutic laser may be incorporated alongside individualized exercise, manual therapy, movement assessment, and performance-based rehabilitation when clinically appropriate.
The goal is not simply to treat a symptom. It is to help you move better, recover with purpose, and return to the activities you enjoy.
Frequently Asked Questions About Photobiomodulation Therapy
What is photobiomodulation therapy?
Photobiomodulation therapy is a non-invasive treatment that uses specific wavelengths of red or near-infrared light to influence cellular and tissue processes. It is also sometimes called low-level laser therapy or low-level light therapy.
What does photobiomodulation therapy do?
Research suggests that PBM may influence cellular signaling, inflammation, pain, and tissue recovery. Clinical effects vary depending on the condition and treatment parameters.
Is photobiomodulation the same as laser therapy?
PBM describes a therapeutic approach involving light, while laser therapy describes one way that light can be delivered. Some therapeutic lasers are used to provide PBM.
Does photobiomodulation reduce pain?
Research suggests PBM can reduce pain in some conditions, including certain musculoskeletal disorders. However, results vary by diagnosis and treatment protocol.
How long does photobiomodulation treatment take?
Treatment time varies depending on the device, treatment area, wavelength, dose, and clinical goal. There is no single treatment time that applies to every patient.
Is photobiomodulation safe?
PBM is generally considered well tolerated when appropriately administered. A qualified healthcare professional should determine whether it is appropriate for an individual patient and follow the safety requirements for the specific device.
Can PBM replace exercise-based physical therapy?
No. PBM should generally be considered an adjunct to rehabilitation rather than a replacement for therapeutic exercise and other evidence-based physical therapy interventions.
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