BACKGROUND: The COVID-19 pandemic caused unprecedented disruption to healthcare services worldwide with well-documented detrimental effects on mental health. Patients with refractory disorders of gut-brain interaction such as Irritable Bowel Syndrome (IBS) seen in tertiary care tend to exhibit higher levels of psychological comorbidity, but the impact of the pandemic on IBS symptom severity in tertiary care is unknown. METHODS: As part of routine clinical care, consecutive tertiary referrals with refractory IBS patients prospectively completed a series of baseline questionnaires including IBS symptom severity score (IBS-SSS), non-colonic symptom score, Hospital Anxiety and Depression (HAD), and Illness impact scores. The symptom severity questionnaire data were compared for consecutive patients seen in tertiary care 12 months before and after the onset of COVID-19 pandemic restrictions. KEY RESULTS: Of 190 consecutive tertiary referrals with IBS, those seen during the pandemic had greater IBS severity (IBS-SSS: 352 vs. 318, p = 0.03), more severe extra-intestinal symptoms (non-colonic score: 269 vs. 225, p = 0.03), sleep difficulties (p = 0.03), helplessness and loss of control (p = 0.02), but similar HAD-Anxiety (p = 0.96) and HAD-Depression (p = 0.84) scores. During the pandemic, unmarried patients (p = 0.03), and keyworkers (p = 0.0038) had greater IBS severity. CONCLUSIONS AND INFERENCES: This study has shown for the first time that patients seen in tertiary care with refractory IBS during the COVID-19 pandemic had a significantly higher symptom burden emphasizing the importance of gut-brain axis in IBS. Furthermore, lack of support and perceived loss of control appear to be contributory factors.