[xogap]

It's known that mixing dxm with terfenadine (seldane) is really bad (mostly because of irregular heart rate) and can even be fatal...however my qeustion is, is it just as dangerous to mix dxm with allegra (Fexofenadine) which is an active derivative/metabolite of terfenadine. Basically, when you take terfenadine/seldane your body metabolizes most of it into fexofenadine/allegra. If yes then what should the abistinence from allegra period be before taking dxm?

Thanks