The Original Coldsore light treatment device uses an invisible frequency of Light to stimulate your skins own defenses when an attack of (HSV-1) Herpes simplex "A Coldsore" occurs. The frequency of the light is 1.072 um or 1072 nm and although it is invisible to the eye (somewhat lie a TV remote control), it is at the correct frequency to stimulate your skin into preparing for the Cold sore. This in turn stops the cold sore before it can start. The perfect time to use the Virulite is at the first sign of coldsore attack (Tingle) used at tingle stage the coldsore, in most cases never appears. The Virulite has up until recently been prescribed by NHS GPs. It is now only available to buy. It is a proven effective treatment and has actually been reported to reduce outbreaks after a few uses. The products reviews speak for themselves.