Transcranial PBM
Chapter 2

3 - Safety Profile

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Established Safety Record

Transcranial photobiomodulation has demonstrated an exceptional safety profile across multiple clinical trials totaling over 1,400 patients in stroke studies alone, with additional hundreds of participants in dementia, TBI, depression, and other neurological condition trials. The NEST (NeuroThera Effectiveness and Safety Trials) series, which included three large studies (NEST-1 n=120, NEST-2 n=660, NEST-3 n=630), found no significant differences in rates of adverse events between NIR light treatment and sham exposure.​

Common minor side effects reported include mild headaches, perception of vivid colors, transient irritability, unusual tastes in the mouth, and occasional mild dizziness likely from peripheral vasodilatory effects. These effects are typically mild, transient, and resolve without intervention. Long-term follow-up studies have reported no serious adverse effects, delayed complications, or safety concerns even with daily administration for 12 weeks.​

The non-thermal nature of low-level laser therapy is critical to its safety profile. At the power densities employed (typically <400 mW/cm²), tissue heating is negligible and produces no physical damage. Studies using thermography and computational modeling confirm that the effects are photobiochemical rather than thermal.​

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