A 54-year-old woman presented to our hospital with watery diarrhea and abdominal pain for 1 month since she started escitalopram for depression. Physical and laboratory examinations were normal. On colonoscopy, only slight redness in the rectum was observed. The majority of biopsy specimens showed collagen bands in the subepithelial layer. She was diagnosed with collagenous colitis (CC). After discontinuation of escitalopram, her symptoms disappeared. Recently, some endoscopic findings of CC have been proposed, but over 80% of cases have no significant findings in many reports. Therefore, we propose that, in cases of chronic watery diarrhea, enough biopsies should be taken even if no abnormal endoscopic findings are observed.
