Complex sentence: Antimotility medication has a theoretical risk of causing complications, and although clinical experience has shown this to be unlikely, these drugs are discouraged in people with bloody diarrhea or diarrhea that is complicated by fever.
Split into simpler sentences: Antimotility medication has a theoretical risk of causing complications, but clinical experience has shown this to be unlikely. These drugs are thus discouraged in people with bloody diarrhea or diarrhea complicated by fever.