Effect of Tofacitinib on Coagulation and Platelet Function, and Its Role in Thromboembolic Events

This study investigates whether tofacitinib — a medication used to treat ulcerative colitis (UC), an inflammatory bowel disease — affects blood clotting and platelet function, and whether those effects are linked to the increased risk of blood clots (thromboembolism) seen with this drug class. **You may be eligible if...** - You are over 18 years old - You have been diagnosed with ulcerative colitis according to established criteria - Your treatments have been stable for the past 3 months - If you have active UC, you had an endoscopy within the past month showing active disease - Women of childbearing age are using highly effective contraception (IUD, bilateral tubal ligation, partner vasectomy, or abstinence) - People without UC may also participate as a comparison group **You may NOT be eligible if...** - You have a known bleeding disorder or are on anticoagulants that would affect the study results - You have had a recent blood clot or stroke Talk to your doctor to see if this trial is right for you.