My understanding is that the dosage of Naltrexone we take essentially wears off in about 4 - 6 hours... overnight. As for Imodium, it was also my understanding that using it with Crohns was not advised anyway... regardless of LDN or not. Anecdotal info I heard on this site long before LDN ever came up was that using Imodium, or more to the point, the over use of it, was taboo for Crohns. I think this is an area that demands clarification, so if there are any members out there with info pro or con about Imodium in general, or with specific info regarding it and LDN... please feel free to toss in your 2 cents worth.