I did a lot of reading about using red and blue light to help acne. There is a lot on the Web, but they ALL say that it is best to use them separately -- otherwise you get purple light, which doesn't do anything. Verilux has been selling these for years and have NO clinical data on this particular product - according to their customer service people - they only refer to some old research that was NOT done with their product -- DON'T BUY IT!!