INTRODUCTION: Sense of discomfort, which is experienced in daily encounters, can develop into stress, coexist with stress, or interplay with self-efficacy. This study presents two objectives, namely, to develop and test a new instrument called the Emotional Discomfort (EmoD) Scale and to compare the EmoD with the General Self-Efficacy (GSE) Scale. METHODS: The study was conducted in an urban primary healthcare center in Greece over a three-week period in 2020. Out of 314 individuals invited to participate, 263 accepted and completed the questionnaire. The EmoD is a five-point Likert-type eight-item scale for assessing individual reaction and sense of discomfort in daily life situations. RESULTS: Cronbach's α for the new scale reached 0.730 (acceptable reliability). Participants who used psychotropic drugs scored higher in the EmoD scale compared with nonusers. GSE scores showed reverse associations with EmoD scores. Multiple linear regression analysis indicated that an increase in self-efficacy, as measured using the GSE scale, was associated with a reduction in sense of discomfort, as measured by the EmoD scale. CONCLUSIONS: The use of the EmoD scale can aid health or social care providers in detecting levels of emotional discomfort, a finding that is demonstrated to interplay with self-efficacy. Future studies employing the use of this new instrument could examine emotional discomfort in relation to stress coping and social isolation.