Imodium does not prevent the onset of diarrhea and is not meant to be taken before diarrhea occurs.
Only take the Imodium when you actually have diarrhea and it will work to stop diarrhea quickly so you don't have to worry about the diarrhea.
When you get the diarrhea take the Imodium right away and within an hour or so the diarrhea should stop and you should feel better.
I've taken Imodium when I have diarrhea and sometimes it's worked as fast as an hour after taking it so Imodium does work well for treating and stopping diarrhea.
Imodium also contains another ingredient that is called Simethicone, which helps to ease excess gas in the intestines and relieves bloating and pain due to gas.
So the gas and bloating will be relieved as well as the diarrhea you have.