Adequate perception of bodily sensations is essential to protect health. However, misinterpretation of signals from within the body is common and can be fatal, for example, in asthma or cardiovascular disease. We suggest that placing interoceptive stimuli into interoceptive categories (e.g., the category of symptoms vs. the category of benign sensations) leads to perceptual generalization effects that may underlie misinterpretation. In two studies, we presented stimuli inducing respiratory effort (respiratory loads) either organized into categories or located on a continuous dimension. We found pervasive effects of categorization on magnitude estimations, affective stimulus evaluations, stimulus recognition, and breathing behavior. These findings indicate the need for broadening perspectives on interoception to include basal processes of stimulus organization, in order for interoceptive bias to be understood. The results are relevant to a wide range of interoception-related phenomena, from emotion to symptom perception.