Do the fruit-flavored tobaccos that are widely used in hookahs require a Kashrut certification similar to foodstuffs? If yes, why; if not, why not?
According to the cRc they probably do. However I disagree. Se what I have written here. The same argument applies here as well, except with an added leniency: You don't know whether there is non-kosher stuff inside there, and even if there is, it is mixed into the tobacco and unrecognizable. Thus it could be said that even the Rema would agree to be lenient here l'chatchila. For further elaboration, see what I have written in this blog post.