I have been on Singulair for about a month. When I was first prescribed it I was very ill Sinus infection and phenomena. So my nose was stuffy and I could not smell or taste (from being sick). So as the weeks passed and I did not get my taste or smell back I was concerned. Singulair is the only new thing in my life so I have to point to it. I also have been having Very bad noose bleeds a few times aday. My sinuses and back of throat feel numb. I have been very angry/irratable( I just thought PMS or something) now seeing other peoples claims I realize that too is from Singulaie. My stomach has been very upset too. Constant bathroom visits. I could see how a child could have an accident. So I will discontinue