Clinically, low level laser therapy (LLLT) has been used successfully in the treatment of chronic pain but many have questioned the scientific basis for its use. Many studies have been poorly designed or poorly controlled. A double-blind, placebo-controlled, random-allocation study was designed to analyse the effect of second daily infrared (IR) laser (820nm, 25 mw) and visible red laser (670 nm, 10 mw) at 1 J/cm2 and 5 J/cm2 on chronic pain. Forty-one consenting subjects with chronic pain conditions exhibiting myofascial trigger points in the neck and upper trunk region underwent five treatment sessions over a two week period. To assess progress, pain scores were measured using visual analogue scales before and after each treatment. The incidence of side effects was recorded. All groups demonstrated significant reductions in pain over the duration of the study with those groups which received infrared (820 nm) laser at 1 J/cm2 and 5 J/cm2 demonstrating the most significant effects (p < 0.001). Only those subjects who had active laser treatment experienced side effects. Results indicated that responses to LLLT at the parameters used in this study are subject to placebo and my be dependent on power output, dose and/or wavelength.

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