A hand-held, battery-powered, portable device designed to be used by a layperson to emit infrared light intended as therapy to reduce the duration of cold sores caused by the herpes virus (herpes labialis). It typically consists of a self-contained unit, light-emitting diodes (LEDs), an internal microprocessor and software, activation control and signal light, and disposable batteries. Upon application, it emits infrared light (wavelengths around 1072 nm) to the dermis of the affected area of an erupting cold sore for a pre-set period of time (e.g., few minutes) and provides a signal to the user when the treatment is complete.