I cycled across Vietnam a couple of years ago. I lasted the entire 10 days without any GI-related problems, and made it to the last hotel with 2 days remaining of my trip. It was then that I started to get severe stomach cramps and was basically bed-ridden for the last 2 days while everyone else went on a trip to see the Mekong Delta.

So I was taking Imodium to try to help with the fact that I was basically shitting water every hour while my guts twisted themselves into knots. Worst stomach pains I've ever had. Eventually we had to leave so I just about made it from taxi to airport and got on the plane without shitting my pants.

Then came the rest of the 30 hour trip home, involving a stop-over in South Korea. Those long-haul flights were fucking hell. I was so glad to get home to my bed (again, I just about made it home without shitting my guts out in the car). Anyway, I went to the doctor the next day and he told me taking Imodium the whole time was the worst thing I could've done, as I basically just kept all the nasty bacteria and stuff in my gut and dragged out the suffering far longer than I needed to.

TL;DR: If you are sick and have the shits, don't use Imodium. Just let it out.