As adjectives the difference between gastrointestinal and antimotility
is that gastrointestinal is of or pertaining to the stomach and intestines while antimotility is reducing gastrointestinal motility (in the treatment of diarrhea).
gastrointestinal
English
Adjective
Of or pertaining to the stomach and intestines.
antimotility
English
Adjective
(-)
(medicine, of drugs) Reducing gastrointestinal motility (in the treatment of diarrhea).