Inflammatory bowel disease (IBD) affects 300,000 people in the United Kingdom (UK). The condition is characterised by periods of remission and relapse. Forty percent of people with IBD in remission and 72-86% of people with active IBD report fatigue to be their most troublesome symptom. IBD-fatigue affects people’s daily functioning and impacts on their quality of life. However, there is limited understanding of the concept of fatigue and the impact that fatigue has on the everyday life of people with IBD. There are no previous studies exploring how people try to manage IBD-fatigue on a daily basis. Aims: This study aims to explore the concept of fatigue as experienced by people with IBD, what impact fatigue has on their lives, and how they manage it. Methods: Descriptive phenomenology was used to achieve the aims of the study. One-off in-depth interviews were conducted with twenty participants. Interviews were digitally recorded and transcribed verbatim. Data were analysed using Moustakas’ method (1994). This involved analysing the data at individual and group levels for textural and structural descriptions. Results: Five main themes, with many textural and structural sub-themes were identified. A wide range of terminology, including metaphors and similes, were used to describe fatigue reflecting its complicated and complex nature. Fatigue was presented as invisible, unpredictable, with constantly fluctuating daily patterns and severity. This made reporting fatigue difficult and at times lead to participants being challenged about its authenticity. The array of physical, psychological, cognitive and situational factors were perceived to contribute to fatigue, and different methods (e.g. sleep and rest, pacing, energy preservation, exercise, stress reduction, asking for help) were attempted by participants to manage fatigue. Most methods were not used systematically, possibly resulting in their apparently limited effectiveness. Impact of fatigue was perceived as negative, with participants constantly comparing their life and themselves as they were before fatigue and how much they have lost. They felt that fatigue is in control of their life and each day they had to fight another battle to defeat fatigue. Participants felt imprisoned in their fatigued unreliable body leaving them frustrated, isolated and lacking self-confidence. They reported loss of self and self-identity, resisting to accept the ‘new fatigued me’. Conclusion: Due to its complicated and complex nature, IBD-fatigue is not fully understood by individuals affected by it, and they have difficulties clearly explaining it to others. The invisibility of IBD-fatigue often leads to its existence being questioned by self and others. The negative and debilitating impact of IBD-fatigue affects all aspects of an individual’s life. Individuals affected by IBD-fatigue need support from healthcare professionals to help them to understand and manage this complex symptom. The findings from this study need to be taken into consideration by healthcare practitioners involved in the care of IBD patients. To fully understand the phenomenon of fatigue a longitudinal study is required to explore fatigue over time.