Irritable bowel syndrome (IBS) is a health challenge in Denmark, especially among young and middle‐aged people. It raises questions about control, alienation, responsiveness, and responsibility in relation to the body in welfare societies. Based on long‐term ethnographic fieldwork, this article explores how young and middle‐aged Danes diagnosed with IBS inhabit and relate to their bodies. Previous studies have described how IBS patients experience their bodies to be unreliable, unpredictable, and embarrassing. Drawing on phenomenological explorations of bodily alterity, we argue that the gut transforms into “an other” for the afflicted. It is involved in a restless process in which it sometimes emerges as “me,” sometimes as “not‐me,” and sometimes as “not‐not‐me.” People attempt to theorize and control their gut trouble, yet it continuously escapes their grasp. How do people live with and care for such an alienness‐within? Does an IBS diagnosis make bodies feel more or less alien?