High-Power Laser Therapy: What It Treats and What to Expect

Quick answer. High-power laser therapy (also called Class 4 laser or photobiomodulation) uses red and near-infrared light to stimulate cellular repair in soft tissue. The strongest published evidence is for tendinopathy: plantar fasciitis, tennis elbow, Achilles, and shoulder rotator cuff. It is not a stand-alone treatment. At Medstar, we use it inside a physiotherapy session to support hands-on care and an active loading plan, not to replace them.

Patients ask us two questions about laser therapy more than any others. Does it actually do anything, and how is it different from the cold laser at the clinic down the street. Both are fair questions. The answers depend on the specific laser, the specific condition, and what the laser is doing inside the session, not on marketing claims about light.

This is the long version of what we tell patients in the room.

What does "Class 4" actually mean on a therapeutic laser?

Class 4 is a laser-safety classification under the IEC 60825 standard, not the device-risk class Health Canada uses for medical-device licensing. The two systems share numbers and that confuses everyone. Under the safety standard, a Class 4 laser produces enough optical output (above 500 mW) to cause eye injury and skin burns from the direct or reflected beam. Per Health Canada's guidance on laser products, therapeutic laser devices used in clinics fall under the Medical Devices Regulations and require a medical device licence regardless of the optical class.

The practical difference for a patient is power. A Class 4 unit delivers more energy per pulse than the typical "cold laser" or low-level laser therapy (LLLT) device, which usually operates at Class 3B or below. More energy reaches the target tissue in the same amount of time. It also means everyone in the room wears wavelength-appropriate eye protection. No version of a Class 4 session runs without goggles.

How is high-power laser supposed to work in the body?

The accepted mechanism is photobiomodulation: red and near-infrared photons are absorbed by cytochrome c oxidase in the mitochondrial electron transport chain. That absorption is thought to displace nitric oxide bound to the enzyme, which removes a brake on cellular respiration and increases ATP production in the irradiated tissue. The downstream effects most relevant to rehab are a reduction in pro-inflammatory signalling and a shift in the local oxidative environment that supports tissue repair. The current literature on the mechanism is summarised well in de Freitas and Hamblin, 2016, in the IEEE Journal of Selected Topics in Quantum Electronics.

What that does not mean: laser does not "kill pain" by blocking nerve signals, and it does not restructure tissue in a single session. It is a biological dose-response. That is why dosage matters more than the marketing wattage on the brochure.

Where is the evidence for laser therapy strongest?

The strongest published evidence is in tendinopathy, particularly when laser is dosed in line with the World Association for Photobiomodulation Therapy (WALT) recommendations and combined with active rehab.

• Lower-extremity tendinopathy and plantar fasciitis. A 2022 systematic review and meta-analysis (Wang et al., BMJ Open) found that LLLT significantly reduced pain and disability in lower-extremity tendinopathy and plantar fasciitis in the short and medium term.
• Shoulder tendinopathy. A 2015 systematic review in Physiotherapy Research International (Haslerud et al.) found clinically important pain relief from LLLT both as monotherapy and as an adjunct to exercise.
• Lateral epicondylitis (tennis elbow). Trials following WALT-dose protocols at 904 nm have shown grip-strength gains over sham. The WALT dosage tables are the closest thing the field has to a treatment manual.

In our clinic, the laser is most often paired with manual therapy and a loading program for these exact conditions. Patients who arrive with an Achilles tendinopathy, a stubborn lateral epicondylitis, or a chronic plantar fascia case are the ones we expect to benefit. We do not treat them with laser alone. The loading is what changes the tendon. The laser supports the early phase when irritability limits how much load the tendon will tolerate.

Where is the evidence weaker?

Honesty matters here, because patients ask. Knee osteoarthritis has mixed evidence. A 2024 network meta-analysis (Liu et al., Aging Clinical and Experimental Research) found LLLT superior to sham for pain but not for function or stiffness. Earlier reviews were less favourable. Laser therapy is not part of the major knee-OA clinical practice guidelines. We may use it when pain is limiting a patient's ability to start active rehab, but it is not a primary tool for knee OA in our hands.

The same caution applies to chronic non-specific low back pain, fibromyalgia, and post-operative wound healing outside the indications a surgeon has explicitly approved. The literature includes positive studies for all three, but the heterogeneity in dose, wavelength, and protocol makes it hard to generalise. We will tell you when we think laser is the right call and when we think your time is better spent on the manual-therapy and active-rehab side of the session.

What does a laser session at Medstar actually look like?

A first session involving laser is part of a regular physiotherapy initial assessment, not a separate treatment booking. The physiotherapist screens for the usual contraindications: known photosensitising medications, suspected malignancy in the treatment field, pregnancy over the abdomen or lower back, active epiphyseal growth plates in paediatric patients, and a few others. If laser is appropriate, we set a dose based on the WALT recommendations for the tissue and depth, then move the handpiece over the affected area for the prescribed time. The patient and the physiotherapist both wear wavelength-specific goggles.

Most laser applications last three to ten minutes per region within a longer session. Patients often feel a gentle warmth. That is expected and is part of the dose response, not a tissue burn. After the laser portion we usually move directly into hands-on work and the exercise plan. The point of the modality is to make the rest of the session more productive, not to replace it.

How long it takes to feel a difference depends on the condition, the tissue, and how acute or chronic the case is. In our clinic we usually reassess after the first block of sessions. We are looking for a measurable change in pain irritability, range of motion, or load tolerance, not just "it feels a bit better." If we are not seeing that change, we adjust the dose, change the modality, or escalate the active rehab. Laser is one tool, not the answer to the question.

When is laser worth trying, and when is it not?

Five clinical situations where we will usually offer it:

• A tendinopathy that is too irritable to load at a meaningful dose yet, where loading still hurts more than it helps.
• A chronic insertional tendon problem (lateral epicondyle, Achilles, plantar fascia) that has plateaued under loading alone.
• A localised soft-tissue injury where the patient needs faster symptom relief to keep working or training.
• Post-surgical soft tissue once the surgeon has cleared the field for therapy.
• An MVA-related soft tissue injury under ICBC where we are trying to keep the active-rehab window open within the first 12 weeks.

Conditions where we will usually tell you laser is not the right tool: radicular low back pain with a clear neurological pattern, suspected red-flag pathology, fracture care outside the surgeon's referral, and most cases where the limiting factor is movement re-education rather than tissue irritability.

A practical note on cost and coverage

Laser therapy at Medstar is delivered inside a physiotherapy session. There is no separate "laser appointment" fee. The session is billed as a physiotherapy visit, which means the standard direct-billing rules apply: extended health, ICBC, WorkSafeBC and MSP supplementary all run through the same billing flow on a physiotherapy line. Current rates and the booking page are on Jane App. If you are unsure whether laser is in scope for your specific funding, message us through the contact page before your first visit and we will check.

The strongest outcomes happen when laser is one part of a session that also includes hands-on assessment and a loading plan you actually follow between visits. The laser does not replace the work. It makes the work tolerable earlier in a flare-up.

Frequently asked questions

Does high-power laser therapy actually work?

The evidence is strongest for tendinopathy and plantar fasciitis when laser is dosed correctly and combined with active rehab. The evidence is mixed for knee osteoarthritis and weaker for chronic low back pain. Results depend on dose, wavelength, condition, and whether the rest of the rehab plan is in place.

Is Class 4 laser better than cold laser?

Class 4 delivers more optical power per pulse than cold laser (Class 3B and below). More power can mean shorter treatment times and deeper tissue penetration, but dose is what matters clinically. A well-dosed Class 3B session and a well-dosed Class 4 session can both be effective. The class number alone is not the deciding factor.

How many laser sessions will I need?

It depends on the tissue and how acute or chronic the case is. In our clinic we reassess after the first block of sessions and adjust based on measurable changes in pain, range of motion, or load tolerance. We do not pre-sell session packages.

Does laser therapy hurt?

No. Most patients feel a gentle warmth over the treatment area during the application. Sharp pain or a burning sensation is not expected and should be reported to the physiotherapist immediately. Eye protection is mandatory for both the practitioner and the patient.

Is laser therapy covered by ICBC, WorkSafeBC, or extended health?

Laser is delivered inside a physiotherapy session at Medstar and is billed on a physiotherapy line, so the standard funding rules apply. ICBC, WSBC, MSP supplementary, and most extended-health plans cover physiotherapy visits. If you want to confirm before booking, contact us with your specific funding details and we will check.

This article is general information, not personal medical advice. A regulated practitioner can confirm whether the patterns described apply to you.

Sources

• de Freitas LF, Hamblin MR. Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy. IEEE Journal of Selected Topics in Quantum Electronics (2016)
• Wang et al. Efficacy of low-level laser therapy in patients with lower extremity tendinopathy or plantar fasciitis: systematic review and meta-analysis of RCTs. BMJ Open (2022)
• Haslerud et al. The Efficacy of Low-Level Laser Therapy for Shoulder Tendinopathy: a systematic review and meta-analysis. Physiotherapy Research International (2015)
• Liu et al. Optimal wavelength of LLLT for knee osteoarthritis: network meta-analysis. Aging Clinical and Experimental Research (2024)
• WALT (World Association for Photobiomodulation Therapy): Dosage recommendations, 904 nm (revised October 2022)
• Health Canada: Guidance for laser products, scope of the regulations