Molly Harte ^1* John Macken ^1,2 Lifong Zou ³ Farida Fortune ^1,2,4*

• ¹ Royal London Hospital, Barts Health NHS Trust, London, England, United Kingdom
• ² Centre for Oral Immunobiology and Regenerative Medicine, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, England, United Kingdom
• ³ Centre for Oral Bioengineering, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, England, United Kingdom
• ⁴ London Behcet’s Centre of Excellence, The Royal London Dental Hospital, Barts Health NHS Trust, London, United Kingdom

Crohn's disease (CD) is a chronic inflammatory bowel disease which can affect any area of the gastrointestinal tract, including oral tissues. The complex nature of this disease poses demands interdisciplinary management, especially when both intestinal and oral manifestations are present.This report presents the case of a 28-year-old male patient with oral, ileo-caecal and peri-anal CD managed jointly between Gastroenterology and Oral Medicine. Treatment with vedolizumab, an α4β7 integrin with gut-selective anti-inflammatory activity, resulted in excellent ileo-caecal disease control, but was ineffective in controlling oral manifestations. The absence of MAdCAM-1 expression in oral tissues, necessary for vedolizumab's mechanism, meant that the drug's anti-inflammatory effects were limited to the gut. This limitation led to worsening oral symptoms, necessitating concomitant azathioprine therapy to manage oral inflammation.Multidisciplinary collaboration is important when managing CD patients with both oral and gut involvement in CD. Clinicians should be aware that vedoluzimab may be beneficial for intestinal CD, but does not target inflammation in oral tissues due to its gut-specific action. Good knowledge of the pharmacology and mechanism of action of drugs prescribed can aid decision making when prescribing for this group of patients and can limit the need for polypharmacy, often associated with an increased adverse effect profile.