A Study to Observe Real-world Evidence of Guselkumab Treatment in Participants With Ulcerative Colitis and Crohn's Disease in the United Kingdom (UK)

This is a real-world observational study tracking how guselkumab — a biologic drug that targets inflammation — works in patients with moderate-to-severe Crohn's disease or ulcerative colitis (two inflammatory bowel diseases) in real clinical settings in the UK, outside of a controlled trial. **You may be eligible if...** - You have been diagnosed with moderate-to-severe Crohn's disease or ulcerative colitis - Your doctor has decided to prescribe guselkumab based on approved guidelines for your condition - You enroll before or at the time of your first dose of guselkumab - You can sign a consent form allowing your records to be used for research **You may NOT be eligible if...** - There is a medical reason you should not take guselkumab (a contraindication listed on the drug label) - You are currently enrolled in an interventional clinical trial of guselkumab Talk to your doctor to see if this trial is right for you.