Facts and myths about Low-Level Laser Therapy

By Jan Tunér

There are many myths and city tales about LLLT/PBM. Let us have a look on some of the most common ones!


There are lasers where the light is combined with a magnet. Magnets may or may not have a beneficial effect on things like inflammation and pain, but there is no evidence for any positive effect when these two therapies are combined. And the depth of penetration is not affected at all, the photons are not affected by the magnetic field.


This misconception seems to have eternal life, no matter how often it has been refuted. When low level lasers were initially introduced, they were obviously included into the safety requirements of electrotherapeutic devices. But lasers are based upon light, not electricity. Pacemakers cannot be influenced by light. Full stop.  [NB:  There are some devices on the market that combine ‘multiple radiance sources, such as static magnets and/or pulsed magnetic fields, and/or electrical stimulation, with laser and/or LED sources in the application head (see e.g. ‘Magnets’, above). Whilst the light-emitting components will not affect the performance of a pacemaker, the safety of these specific multi-radiance devices should be considered on the basis of these additional energy sources. (PAJ, Ed.)]

Solitons and scalars

There are many “home tailored” theories in the market. Some stem from alternative medical circles where auras, levitation, homeopathy are cherished. “Soliton waves” and “scalar waves” are a couple of home tailored fabrications and do not exist in PBM units at all. http://www.laserannals.com/2016/02/06/the-end-of-the-soliton-laser/


There are so far only some suggestions that PBM could reduce the development of diabetes. But there is evidence that PBM can reduce a very serious side effect of diabetes: impaired wound healing. http://www.laserannals.com/2016/12/04/photobiomodulation-pbm-and-diabetic-wounds/


There are many opinions about the penetration of light. From 13.5 cm to 2 mm. Most of the claims are incorrect or incomplete. The penetration differs with the wavelength, with the type of tissue and with the technique used (irradiation from a distance, contact, firm contact). Be critical about too optimistic claims, and stay convinced that laser therapy cannot be performed through clothes. And do not believe that 980 nm can penetrate deeper than 808 nm. http://www.laserannals.com/2013/01/22/the-penetration-of-laser-light-a-simple-demonstration/

Green laser pointers

Newspapers, ophthalmologists and even government officials often claim that the green laser pointers can make a person blind. If we limit ourselves to 90% of incidences with “green laser attacks”, these lasers are in the range 5-100 mW and are harmless for the eye. To hit the eye of a car driver arriving at some 50 km/h more than a millisecond is hardly possible. But it is very irritating and distracting and very bad for traffic safety. To ban them is correct, but rest assured that your eyes are safe. The remaining use of high power green laser attacks is another matter. But still not as bad as press report tend to suggest.

Eye safety

Class 3B laser are uncollimated and safe. Using protective goggles on the patients serves three purposes: suggesting high tech, making the patient feel safe and complying with governmental requirements. There are no verified reports about ocular injuries caused by 3B lasers. http://www.laserannals.com/2016/02/06/637/

Pulsed or not pulsed

Some manufacturers claim that certain pulse repetition rates are favorable for certain biological conditions. Maybe so, but right now we know very little about this and the “recommendations” are personal guesswork. Some lasers are pulsed out of necessity to reduce heat accumulation in tissue and some are pulsed to save the diode from overheating (GaAs lasers for instance). http://www.laserlessons.info/wp-content/uploads/2017/06/4.-Pulsing-and-contra-indications.pdf

Radiation therapy

Patients subjected to radiation therapy should not be subjected to laser therapy, according to some sources. This belief was proven wrong already in 1965 and the evidence tells us that PBM is the best method possible to avoid the side effects of radiation therapy such as mucositis and xerostomia. http://www.laserannals.com/2016/02/06/photobiomodulation-for-oral-mucositis-a-breakthrough/


Only oncologists are legally allowed to treat cancer. Fair enough. But suppose there is an unknown malignancy in the area? Research shows that cancer cells can be stimulated in vitro (alone in a Petri dish) but in vivo there is the immune system working the other way around. And PBM stimulates the immune system. http://www.laserannals.com/2015/09/05/559/


Some sources claim that PBM should not be used on pregnant women. Nobody has even provided any support for this claim. Acupuncturists claim that there are “forbidden acupuncture points” over the abdomen. For safety reasons only, these could be avoided but other than that the fetus should benefit from a mother without pain or inflammation.

Thyroid gland

Irradiation of the thyroid is a case for the specialist, but the fear of letting laser light occasionally cover the thyroid is exaggerated. In some cases, it has even been an effective treatment method. http://www.laserannals.com/2013/03/24/lpt-contraindications-some-facts-and-some-myths/

Light sensitivity

Claims have been seen that light sensitive patients should not be treated with PBM. For instance, patients taking St. John’s-wort. This is probably true for wavelengths below 500 nm but there are no reports of such a phenomenon when wavelengths in the PBM range (600-1100 nm) have been used.


Pulsing light can trigger an epileptic attack, this is well known. But if the patient cannot see the light? Evidence supporting this concern is lacking.