I began taking this product weeks before I started my musical of Titanic - about a good 4 or 5 weeks before the opening nite; there was NO way I could come down sick. I was told take 3 to 4 tablets of this product daily to prevent colds. On opening nite of the musical I was playing J. J. Astor, I had the worse severe headcold of my life - on opening nite! I hardly made it to the theater with a headcold so bad in my eyes but made it there and made it thru the play. I didn't give up on this product right yet as I have a friend from a previous play that takes this product and she swears by it.... so i continued taking it. 2 weeks after closing performance of Titanic, came down sick with another headcold. Tonsils are swollen and a Cough is coming on... another headcold coming on