<unk>  refers to two medical conditions which cause diarrhoea: collagenous colitis and lymphocytic colitis. Both conditions are characterised by the following triad of clinicopathological features:
Microscopic colitis
Allergic colitis
Chemical colitis
Pseudomembranous colitis
Drug-induced colitis
Ulcerative colitis
Ischemic colitis
Crohn's disease