LLLT Safety

Category:Treatments -> LLLT


Three common questions arise frequently regarding laser therapy and they are “Will LLLT harm or permanently damage my eyes?”, “Will LLLT cause cancer/tumors?”, and “What happens if I get to too much exposure to LLLT?”  This page will address those concerns, as well as other misc concerns such as electro-magnetic fields.

Eye Safety

Coming Soon!


Laser therapy has been studied intensively for decades, and LLLT is absolutely safe with the dosages, energy, and wavelengths that we use for hair loss.  There have been zero cases of LLLT causing cancer or tumors, and in vivo (in the body) exacerbation of existing conditions simply does not occur.


Q: Can LLLT cause cancer?

A: The answer is no. No mutational effects have been observed resulting from light with wavelengths in the red or infra-red range and of doses used within LLLT.

Q: But what happens if I treat someone who has cancer and is unaware of it? Can the cancer’s growth be stimulated?

A: The effects of LLLT on cancer cells in vitro have been studied, and it was observed that they can be stimulated by laser light. However, with respect to a cancer in vivo, the situation is rather different. Experiments on rats have shown that small tumors treated with LLLT can recede and completely disappear, although laser treatment had no effect on tumors over a certain size. It is probably the local immune system which is stimulated more than the tumor.

The situation is the same for bacteria and virus in culture. These are stimulated by laser light in certain doses, while a bacterial or viral infection is cured much quicker after the treatment with LLLT.

There are some very important statements in this quote from -which is the internet’s preeminent collection of laser therapy information.  Most importantly, it states things that we’ve know for years: YES, in vitro (in a test tube), cancer cells, bacteria, and viruses can be stimulated by LLLT -  HOWEVER, and this is the important part, in the body it’s the opposite scenario.  The reason being is that the body’s natural immune system is stimulated to a much greater extent, resulting in a disappearance of small tumors in rats and a quicker cure for viral and bacterial infections in a body that is stimulated by LLLT.  This is documented and proven.

Frequently Misinterpreted Studies

One problem in hair loss forums is that people regurgitate the information they find without understanding all the information about the numbers involved.  There are two instances which continue to surface in forums which seem to “scare” people that haven’t educated themselves yet, and I’ll talk about both of them. 

As will be seen, these are perfect examples of something in which the “Substitution Game” would help most people understand more of the problem that is going on here.  LLLT has confusing numbers that few people critics take the time to understand -which leads to many people making erroneus assumptions.  As you know, eating one packet of a sugar substitute a day should not be viewed as the equivalent of eating one 10-pound bag a day -one dosage will do nothing, but one dosage could do serious damage to you.  I’ll use hair loss-related examples of this when appropriate.

Low-level laser therapy increases tumour growth in skin cancer

High irradiances of low-level laser therapy (LLLT) should not be used over melanomas. Researchers writing in the open access journal BMC Cancer studied the pain relieving, anti-inflammatory ‘cold laser’, finding that it caused increased tumour growth in a mouse model of skin cancer.

Jan M. Bjordal from Bergen University College, Norway worked with a team of Brazilian researchers to carry out the in vitro and in vivo experiments. He said, “LLLT has gained increasing popularity as a treatment for soft tissue injuries and joint conditions. However, there is a shortage of evidence, especially in vivo evidence, about the effects of LLLT in malignant conditions such as melanoma”.

Bjordal and his colleagues applied LLLT to cancer cultures and to mice injected with melanoma cells. Although the treatment did not cause any significant changes in the cell cultures, direct irradiation of the tumor with high-dose LLLT caused a significant increase in tumor mass volume and considerable histological alterations, indicating a worsening of the cancer, in the mice. The researchers write, “A high irradiance (2.5W/cm2) combined with high dose of 1050 J/cm2, can stimulate melanoma tumor growth with distinct histological features in vivo”.

“It is important that this contraindication is implemented into clinical practice so that LLLT can remain a safe treatment”, says Bjordal.

This study -used in context with NORMAL LLLT like we do to try to show that laser therapy is potentially dangerous- is ludicrous.  The numbers that they are using are unbelievably TOXIC, so I would of course expect something like this. 
The first number they give is that they are irradiating the surface of the skin with a 2.5W/cm2 beam.  That “W” is WATTS -and remember, our diodes are 5 “MILLIWATTS”.  We aren’t exactly sure how they calculated their 2.5w/cm2 number, but to put this in perspective… AiXiZ 5mW diodes were independently tested and were found to give 2.0274mW irradiation on the skin at a 2cm height.  In the study, 2.5W can be thought of as 2500mW.  So, if we are comparing 2mW to 2500mW, that’s obviously 1250 times stronger!

Don’t forget, by the way, the malignant cancer was pre-existing… laser energy -even at that toxic level- did not cause this in any way, shape of form.  More than likely, the reason the malignant melanoma tumor was able to grow was because of utter decimation of the healthy tissue/immune system surrounding it that was keeping it in check.

The second number they give is the dose of energy -which is 1050 J/cm2.  If you’ve understood just the basic entry level information about laser therapy, you know that 3-6 Jcm2 is considered optimal, and when you get into the 9-12 J/cm2 range and beyond, it’s considered “BIO-INHIBITORY”.  So… their number, once again, is 1050 J/cm2!  That is 175 TIMES THE AMOUNT OF RECOMMENDED ENERGY.

The “Substitution Game”:
Remember what I said earlier about eating on packet of artificial sweetener vs. 10 pounds?!  Well, lets put this in terms of PROPECIA.  Imagine if a study was released in which it was found that taking 175 pills of Propecia a day could exacerbate cancer cells.  Would people post “panic threads” saying “Oh my gosh, if you take 175 Propecia pills a day… your tumors can grow in size!  Therefore, this Propecia stuff is scary!”  Of course they wouldn’t…  taking 175 ASPRIN A DAY would probably kill you, so it’s not a stretch to imagine that 175 Propecia pills might harm you.  Equating the results of taking an entire six-month-dose of Propecia daily with the standard 1mg dosage is patently absurd -and it would be immediately shot down in the forums by any casual observer.

However, due to the fact that their is so much confusion about LLLT in the hair loss industry -some of which you have to believe is intentional- people don’t take the time to explain what those numbers mean.  If it takes 175 times the amount of a normal dosage before something bad happens with an already pre-existing condition… then I’d classify a normal dosage as “safe”, and so should you.  ...Especially since decades of study backs this up.

In regards to the laser wattage/dosage that they used in this study, I don’t think it’s even possible to get that much total energy from the diodes the average hair loss product is using.  The people that did this study are using ultra-high powered diodes to even achieve that level.  It takes 20 minutes to get 6 J/cm2 with a diffused 5mW diode, so it would take 3500 minutes to get that energy with a regular 5mW diode - 58 hours!

One of the cardinal rules of laser therapy is that all laser therapy is NOT equal.  That is shown here pretty well.  It is simply preposterous to compare the findings of this study to anything that we do with 5mW hair loss diodes.

Effects of low-level laser therapy on malignant cells: In vitro study.

Pinheiro A L, Carneiro Nascimento S, De Barros Vieira A L et al.

The aim of a study by Pinheiro was to assess the effect of 635- and 670-nm laser irradiation on H.Ep.2 cells
in vitro using MTT. It was decided to evaluate the effect of increased doses of laser light on these cells. The
cells, obtained from SCC of the larynx. The cultures were kept either at 5% or 10% of FBS. Twenty-four
hours after transplantation, the cells were irradiated with laser light (5 mW diode lasers; 635 and 670 nm;
beam cross section 1 mm at local light doses between 0.04 and 4.8.10(4) J cm2. For 670 nm, significant
differences in the proliferation were observed between the two concentrations of FBS and between
irradiated cultures and controls. Although the results were not significant, 635-nm irradiated cells also
proliferated more than non-irradiated ones. This occurred under both conditions of nutrition. It was
concluded, that irradiation with 670 nm laser light applied at doses between 0.04 and 4.8104 J/cm2 could
significantly increase proliferation of laryngeal cancer cells.

Anesteziol Reanimatol. 2001 Sep-Oct;(5):47-50.

This is the in-vitro (test tube) study mentioned previously.  It indeed shows that there is an increase of cancer cells -but again, this is in an isolated test tube with no immuno-defense system.  When tests like these are done in actual people/mice/etc., there is no proliferation -and there has been noted REDUCTIONS of cancer cells.

So, in the case of in vitro vs. in vivo with laser therapy and cancer cells, it’s just apples to oranges.  Again, laser therapy has been intensely studied for decades, and the findings do NOT support that any cancer is created or increased in the human body using the diodes regularly used for LLLT.

Examples of “Forum Panic” and the Spreading of False Information

  • 12/27/2009 -

    The original post in this thread is what we’d consider as an “Ivory Tower” post with an “I’m a know-it-all and no one else is qualified” theme, but in reality… it’s an example of someone not being able to accurately assess and come to a logical conclusion with the information in front of them.  The thread then degrades to an anonymous poster talking about “cancer of the hairline” (oh good lord!), and the original poster saying something to the extent of “Yeah, lasers could have increased that” -which is an absolutely bogus claim with zero factual basis.  Once again, LLLT does NOT cause cancer, nor does it spread cancer quicker in the body -the opposite has been proven to be true.  So, when people like “Thorton212” at say “People like OMG are not scientists (clearly states on his site that LLLT does not cause cancer when he is in no way qualified to know and or understand that info) and you need to approach their advice and websites with caution.”, actually… I think we’ve shown that it is actually Thorton212 that needs to get up to speed with the info.

    Frankly, the members of this site strive to be an authorities on LLLT -and we at have never exactly understood why people in other forums like the original poster of that thread have to be so condescending and full of themselves when presenting information.  Regardless of what ignorance or motives may be at play, the Editors at have relationships with some of the leading authorities on LLLT, and the Chief Editor is absolutely “qualified to know and understand this info”.  FFS!

    It’s obvious that the average forum user that is seeking to educate themselves need to approach the original poster’s advice with caution from now on since he can’t even do simple research -as they ALWAYS should do.  Always remember that no matter how intelligent someone sounds in their posts -whether it’s a typical forum poster or even if it’s the Editors and Jounalists here at this site- don’t listen to a word they/we say unless you’ve done your own research and know it to be true by your own findings.

Over-Exposure to LLLT

Coming soon!

Electro-Magnetic Fields

Coming soon!