cause they don't want you to start taking it daily! It does rock, I take it when I need to- if I have to go on a long drive, or an appt., etc. during a flare. Who cares "how" it works, just be happy that you always have something to rely on if need be. I'm pretty sure any anti-diarrheal med will cause a LOT of problems with overuse. It's not that they are so "toxic", per se, but that they immobilize the colon basically. You need to pass stuff eventually!