Took Mucinex Fast-Max liquid cold and sinus. It immediately helped clear out my sinus problem, but I started to see blood in the mucus. The second day I had a full on bloody nose that was fairly severe. Day three the bleeding became extremely severe. My wife called Mucinex and they told her it was a rare but not unheard of side effect, told me to stop taking the medication and are sending a refund. Too bad for the side effect, because the medicine did work other than that.