Functional Diarrhea, also known as functional diarrhoea, is related to diarrhea and microscopic colitis, and has symptoms including constipation, diarrhea and vomiting following gastrointestinal surgery. An important gene associated with Functional Diarrhea is FGF19 (Fibroblast Growth Factor 19), and among its related pathways/superpathways are Signaling by FGFR2 and 5q35 copy number variation. The drugs Loperamide and Gastrointestinal Agents have been mentioned in the context of this disorder. Affiliated tissues include colon and small intestine, and related phenotypes are homeostasis/metabolism and growth/size/body region