Well I've never suffered heartburn in my life. Three times this past month I've gone to bed with painful burning in my upper chest like between the throat and esophogus. It may just be coincidental but it seems to happen when I"m trying to get my ec going and I'm dragging on it hard. I have the njoy pro and the Longer version. I just wondered if it could be caused by the product they use to create the vapor. Anyway, just wondering.