I too keep Immodium or LoMotil in my emergency kit(s) but we probably should all be aware that it isn't a given that you should use it for diarrhea in wilderness emergency situations.

I recently was setting up a kit prior to an Alaska trip and was talking with some MD friends: Family Practice, Surgeon, and an Infectious Disease doc (all experienced outdoorspersons). They agreed (it was scary for 3 docs to agree) that if you slow/stop motility, you trap toxins in your system that need to get out. In the extreme, they are highly dangerous. So they think that if you have safe drinking water... keep drinking and "let'er rip". I don't know if I'll take this advice.. but here it is FWIW.