Side effects, Safety and Contraindications of Low Level Laser Therapy and Low Level Light Therapy


Based on the US Food and Drug Administration (FDA) information sheets for medical devices, low level light therapy devices are categorized as “non-significant risk” products.

After more than three decades of research there are no known major side effects attached to these light therapies.

Reported Side Effects for First-Time Users

– Tiredness (temporary) – probably due to the release of metabolites but the majority report a resurgence of energy
– Headaches (temporary) – from the reactivation of neural connections and increased microcirculation
– Dry throat (temporary) – from the stimulation of renal functions


Over 40 years of accumulated scientific studies on low level light therapy reveal no major contraindication. However, this therapy is not recommended for use in the presence of cancer tumor in the nasal area ( Nasal polyps on the other hand has responded positively).

Energy Safety Issues

Vielight 633 Red

The Vielight 633 Red emits non-laser based irradiation (incoherent light) with a low level energy intensity.

Vielight 655 Prime

The Vielight 655 Prime emits laser based irradiation that is designed to generate very low and safe energy output.

However pointing a laser light to the retina can cause tissue damage and scarring. The danger of this is mitigated by the fact that the Vielight 655 laser does not emit a pure, collimated laser: the light is not completely coherent and has some built-in divergence of about 57 degrees. Human involuntary reflex would also cause immediate blinking when the laser light is pointed to the eye. Nevertheless, precaution should still always be taken and it should not be handled by children without supervision.

Vielight 810 Infrared

The Vielight 810 Infrared emits non-laser based irradiation (incoherent light) with a low level energy intensity. Users should note that light within this electromagnetic range is invisible to the naked eye.