Low level laser therapy shows not enough promise for treating lymphedema

By: Lindsay Davey, MScPT, MSc, CDT
March 28, 2013
Editors: Ryan Davey, PhD and Lindsay Davey, MScPT, MSc, CDT

UPDATE: The below article is interesting, and still mostly valid, but for the most up to date information on laser and lymphedema please see our 2018 review: Lymphedema Laser Therapy Inches Closer to Clinical Utility.

Low level laser therapy is sometimes marketed as a miracle cure.  It’s currently used by a variety of practitioners to treat an enormous list of seemingly unrelated conditions, but little data exists to support many of the claims.  Always on the look-out for a new tool, we were interested in seeing if there were any data on using laser to treat lymphedema.  Interestingly, we found some, and the findings were generally positive.  So do we now use laser to treat lymphedema at our clinic?  No, and here’s why:

Low level laser therapy (sometimes called “cold laser”) has grown in popularity in recent years for the treatment of an expansive range of conditions, from depression in dogs, to rheumatoid arthritis in humans.  Despite this surge in interest, high quality clinical evidence supporting its use has not kept pace.  Nor is there a clear understanding of how laser may work to accomplish the sometimes ‘miraculous’ medical outcomes it purportedly produces.

A small collection of studies have been undertaken to evaluate laser therapy for lymphedema, and positive effects were observed.  The best study to date was a well-designed double-blind and placebo controlled trial (Carati C.J., et al. Treatment of postmastectomy lymphedema with low-level laser therapy: a double blind, placebo-controlled trial. Cancer. 2003 Sep 15;98(6):1114-22).  In this study patients were treated with either laser or placebo (fake laser) in two blocks of treatment.  The first block consisted of 3 treatments a week for three weeks, followed by an 8 week break, and then another block of treatments the same as the first.  The authors observed that 31% of patients experienced a clinically significant reduction in arm volume 3 months after laser treatment compared with only 3.8% of patients in the placebo group.  At first glance this sounds promising.  However, from the perspective of a clinician, this isn’t the whole story.  In fact, the study offers little to support laser use clinically:

1      There is a clear conflict of interest.  The primary author works as a consultant for the company that produces the laser used in the study, and the study was also funded in part by that company.

2      Efficacy in 1/3 of patients means lack of efficacy in 2/3 of patients.  While anything is better than nothing in the absence of a viable alternative, in the case of lymphedema there is a highly effective and clinically supported alternative: Combined (or “Complex”) Decongestive Therapy (CDT).

3      Although the study did demonstrate efficacy in 31% of patients, their data also demonstrates that on average there was NO significant reduction in limb volume in the laser treatment group relative to limb baseline measurements.  While the authors note that maintaining swelling to near-baseline levels is better than continued limb volume growth, the clinical goal (which is possible with CDT) is a reduction in lymphedema rather than simply stasis.

4      No positive effects were observed after a single block of therapy (9 treatments), instead only occurring after two blocks (18 treatments).  This regime is rather intensive from a patient convenience and cost perspective, especially given the relatively modest positive outcomes observed.

5      The handful of studies that have followed up on this work tend to have employed different study designs, and many have methodological concerns that limit the strength of their conclusions.  Many of these did not find statistically significant benefits. The best designed follow-up study utilized an even more intensive regime (3x per week for 3 months) and appeared to demonstrate a significant improvement in limb volume over fake laser when performed in conjunction with lymphedema exercise therapy and education.

6      A sound explanation for how laser therapy could be producing the positive effects observed is absent, and remains absent to date.

7      For this research to be truly clinically relevant, laser therapy should be examined in conjunction with CDT, in order to determine if it could be used to enhance the gains that are possible using the gold standard approach to treatment.

Positive results for a new technique can be exciting, and definitely warrants additional research.  As clinicians we have a responsibility to thoroughly evaluate the tools and techniques we introduce into our practices.  Positive clinical data and glowing marketing claims do not necessarily make for better patient outcomes, or cost-effective patient care. It is important to keep in mind that many positive results are not repeated, and many more are contradicted by follow-up studies.  With very few exceptions, a robust literature base is usually necessary before strong conclusions can be drawn, and current clinical practice responsibly modified.


  1. David Kunashko David Kunashko says:

    Hi Lindsay,

    I was wondering if you’ve read the more recent research on LLLT and lymphedema?
    Your article seemed somewhat biased against LLLT –  “It’s currently used by a variety of practitioners to treat an enormous list of seemingly unrelated conditions, but little data exists to support many of the claims.”
    Are you aware of the recent Cochrane review on frozen shoulder? APTA guidelines on Achilles tendinopathies? Effectiveness of Passive Physical Modalities for Shoulder Pain: A Systematic Review by the Ontario Protocol for Traffic Injury Management Collaboration.? UBC’s toolbox on tendinopathies?
    These are but a few of the much more recent guidelines that indicate LLLT has clinical efficacy – certainly, at least, much more than modalities taught to PTs, DCs, etc.
    I would be pleased to drop by your clinic (if you are located in the southern Ontario area) for a presentation on LLLT.

    Dr. David Kunashko
    Director, Education and Training Meditech International Inc.

    • Ryan Davey Ryan Davey says:

      Hi David,

      Thanks for your comments. We don’t have any conflicting interests when it comes to LLTs, we just haven’t seen enough convincing evidence yet to warrant using one in our clinic. Broadly speaking, the Cochrane reviews and other recent research does suggest that there is reasonable clinical evidence that laser can be somewhat effective for reducing pain, but little or conflicting support for other (possibly more meaningful) outcome measures. Unscientific opinions of laser therapy or other experimental modalities by those who create “guidelines”, “protocols” or “toolboxes” matters very little to us.

      It seems that the most plausible mechanism of action proposed for laser therapy is that it works via localized ‘micro-heating’ as a result of a physics effect known as ‘laser beam speckling’. This speckling phenomenon results in small areas of localized heat. So the data and underlying mechanism does support the assertion that laser may be good for pain reduction. However, based on the research, this pain reduction appears to be similar when compared to that achieved by other modalities (including heating, TENS, acupuncture or ultrasound). So from our clinical perspective, laser doesn’t add much to our current treatment options, and nothing ‘novel’ per se.

      Interestingly, many of the laser devices for sale use laser power and wavelengths that actually are not supported by any clinical data whatsoever. Presumably yours is. Or sometimes these devices incorporate LED lights which are also not supported by any research. (Further to this, the clinical protocols for dosing/parameters to use/therapeutic wavelength/power output required/etc are also all over the place, depending on which paper you read).

      I hope one day clinical research on LLLT will show that laser can provide clear and novel clinical value for specific conditions, and it may yet. We are always looking for new treatment modalities and would welcome using one if it did (hence why we know a bit about laser – because it does have potential).

      Thank you for reaching out to discuss.


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