Key takeaways.
- Strongest evidence: lower-limb tendinopathy and plantar fasciitis, with a 13.15 mm pain reduction on a 100 mm scale.
- Moderate evidence: knee osteoarthritis, best when combined with exercise rather than used alone.
- Mixed evidence: low back pain, where trials significantly disagree with each other.
- Dose decides the result. Trials following recommended dosing did better than those that did not.
- No long-term follow-up data exists. Published benefit runs to about 12 weeks.
Where the evidence is strongest: tendinopathy and plantar fasciitis.
The best single source is a 2022 systematic review and meta-analysis in BMJ Open, which pooled randomised controlled trials of laser therapy in lower-extremity tendinopathy and plantar fasciitis. It compared laser against placebo in 10 trials, against other treatments in 5, and as an add-on in 3.
The result: pain fell by 13.15 mm on a 100 mm visual analogue scale at the end of treatment, with a 95 percent confidence interval of 7.82 to 18.48 mm. Between 4 and 12 weeks later the reduction was still 12.56 mm, so the benefit did not evaporate the moment treatment stopped. Disability also improved, with a standardised mean difference of 0.39 at completion, holding at 0.32 four to nine weeks later. The review also reported no adverse events across the included trials.
Read that honestly. A 13 mm shift on a 100 mm scale is a real, measurable improvement and it is not a cure. The review’s own conclusion acknowledged uncertainty about the effect size because the confidence intervals were wide and large trials were missing.
The dose finding that most clinics skip.
The most useful thing in that BMJ Open review is not the headline number. It is that the authors deliberately split the trials into subgroups based on whether they followed the World Association for Laser Therapy dose recommendations.
Against placebo, the trials using recommended doses reduced pain by 14.98 mm, better than the pooled figure across all trials. Better still, when a correctly dosed laser was added to exercise therapy and compared against exercise therapy alone, pain fell by 18.15 mm with a confidence interval of 10.55 to 25.76 mm. That is the largest effect anywhere in the review, and it comes from the combination rather than from laser by itself.
The practical lesson is that laser is dose-dependent. A session delivering too little energy to the target tissue is a waste of your appointment time rather than a milder version of the treatment.
This is why the operator matters more than the brand of machine, and why we ask what a previous clinic was actually doing when someone tells us laser did nothing for them.
Knee osteoarthritis: promising, with caveats.
A 2023 systematic review and meta-analysis in the Journal of Back and Musculoskeletal Rehabilitation looked specifically at high intensity laser for symptomatic knee osteoarthritis. Nine studies met its criteria and all nine reported positive effects on pain.
The quality picture is where the caution comes in. Of those nine studies, the reviewers rated one as excellent, six as good, and two as fair or poor. Their conclusion was that high intensity laser is a promising and recommended option for knee osteoarthritis pain, especially when implemented in combination with exercises.
That last clause is the whole clinical strategy in one line. We use laser in knee osteoarthritis to reduce the pain that is stopping someone from loading the joint, and then we load the joint. Detail on how that runs is on the knee and shoulder page.
Low back pain: statistically positive, practically messy.
A 2023 meta-analysis in Lasers in Medical Science pooled randomised trials of high intensity laser in adults with low back pain. It found in favour of laser on pain intensity, with a mean difference of 1.65 points, and on two separate disability scales.
The number worth knowing is the heterogeneity: 67 percent for pain and 73 percent for the Oswestry disability index. Heterogeneity that high means the individual trials disagreed with each other substantially, so the pooled average is smoothing over a wide spread of results. Some trials found a lot, some found little.
Our reading is that laser is a reasonable adjunct for a genuinely irritable back that is limiting movement, and a poor choice as the centrepiece of a back-pain plan. Low back pain has too many different drivers for one modality to be the answer.
What the research does not show.
There is no long-term follow-up data. The BMJ Open reviewers said so directly: benefit was measurable to 12 weeks after treatment, and long-term data were not available. Anyone telling you laser produces permanent change is describing something the literature has not measured.
There is also no good evidence that laser works as a standalone treatment. Nearly every trial delivered it alongside rehabilitation, so what has actually been tested is laser plus exercise against exercise alone. That is the honest description of the intervention.
And the trials are small. The recurring criticism across all three reviews is a shortage of large, well-powered studies, which is why the confidence intervals stay wide.
Frequently asked questions.
Does laser therapy actually work, or is it a placebo?
High intensity laser therapy outperforms sham laser in several randomised trials, so the effect is more than placebo, though the size of it is modest. A 2022 BMJ Open review of lower-limb tendinopathy and plantar fasciitis found pain fell by 13.15 mm on a 100 mm scale at the end of treatment against control. Trials comparing laser to a convincing sham are the ones worth weighing, and those are the studies these figures come from.
Which conditions does laser therapy have the best evidence for?+
The strongest published evidence for laser therapy is in lower-limb tendinopathy and plantar fasciitis. The 2022 BMJ Open systematic review pooled randomised trials in those conditions and found significant reductions in both pain and disability that persisted 4 to 12 weeks after treatment ended. Achilles, patellar, and shoulder tendinopathy plus plantar fasciitis are where the case for laser is most defensible.
How much pain relief does laser therapy actually provide?+
In the 2022 BMJ Open meta-analysis, laser reduced pain by 13.15 mm on a 100 mm visual analogue scale immediately after a course, with a 95 percent confidence interval of 7.82 to 18.48 mm. At 4 to 12 weeks the reduction was 12.56 mm. For context, that is a noticeable improvement rather than a transformation, and it was measured in people also doing rehabilitation.
Does laser therapy work for knee osteoarthritis?+
The evidence for knee osteoarthritis is moderate rather than strong. A 2023 systematic review in the Journal of Back and Musculoskeletal Rehabilitation identified nine eligible studies, all reporting positive effects on pain, but rated only one as excellent quality and two as fair or poor. Its conclusion was that laser is a promising option for short-term pain relief, especially when combined with exercise rather than used alone.
Does laser therapy help low back pain?+
A 2023 meta-analysis in Lasers in Medical Science found high intensity laser therapy reduced low back pain intensity compared with control, with a mean difference of 1.65 points and statistical significance. Disability scores improved too. The caution is that heterogeneity between trials was high at 67 percent for pain, meaning the studies disagreed considerably, so the pooled figure hides a wide spread of individual results.
Why does dose matter so much in laser therapy studies?+
Dose decides whether a laser trial shows an effect at all, which is why the 2022 BMJ Open review grouped its trials by whether they followed World Association for Laser Therapy dose recommendations. Trials using recommended doses produced a clearer pain reduction against placebo than the pooled average. An underdosed laser session delivers too little energy to the target tissue to do anything measurable.
Is the evidence for laser therapy high quality?+
It is mixed, and honest reporting matters here. The 2022 BMJ Open review rated its included studies as moderate to high quality but noted wide confidence intervals, a lack of large trials, and no long-term follow-up data at all. The knee osteoarthritis review found only one of nine studies to be excellent quality. Laser has real supporting evidence that falls short of definitive.
How long do the effects of laser therapy last?+
Published follow-up is short. The 2022 BMJ Open meta-analysis measured a sustained benefit 4 to 12 weeks after treatment finished, and explicitly stated that long-term data were not available. So there is reasonable evidence the effect outlasts the treatment course by a couple of months, and no good evidence about what happens after that. Anyone promising permanent results is going beyond the research.
Should I choose laser therapy instead of exercise?+
No, and the research does not support that framing. The knee osteoarthritis review concluded laser works best implemented in combination with exercises, and the tendinopathy trials measured laser alongside rehabilitation rather than instead of it. Progressive loading is what changes a tendon or a joint over months. Laser lowers pain enough to make that loading possible sooner, which is a supporting role.
When would a physiotherapist say laser is not worth it?+
We would steer you away from laser when your main problem is movement control, strength, or a nerve-related pattern rather than local tissue irritability, because lowering local pain does not address any of those. We would also stop if a first block of sessions produced no measurable change in pain, range of motion, or load tolerance. Repeating a treatment that has not worked is not a plan.
Sources.
- Efficacy of low-level laser therapy in patients with lower extremity tendinopathy or plantar fasciitis: systematic review and meta-analysis of randomised controlled trials. BMJ Open, 28 September 2022
- High-intensity laser therapy on pain relief in symptomatic knee osteoarthritis: a systematic review and meta-analysis. Journal of Back and Musculoskeletal Rehabilitation, 2023
- High-intensity laser therapy in low back pain management: a systematic review with meta-analysis. Lasers in Medical Science, 26 July 2023
Sources checked 4 September 2026.
Not sure laser is the right tool?
Book an assessment. We'll tell you honestly whether the laser helps your injury, or whether something else will do more.
Reviewed by Sanaz Davarian, PT, MSc, Owner & Director, Registered Physiotherapist, College of Physical Therapists of British Columbia (CPTBC). Medstar was the first physiotherapy clinic on the North Shore to install a Class 4 high intensity laser.
This page is for general information only and does not constitute medical advice. High intensity laser therapy is one tool among several, and it is not appropriate for every injury or every person. Nothing here is a promise of a particular outcome. Treatment suitability is determined case-by-case during clinical assessment. Physiotherapy at Medstar Sport Physio & Health is provided by physiotherapists registered with the College of Physical Therapists of British Columbia (CPTBC).