Post-authorization, prospective and unicenter clinical trial, in which patients with UC will be included. The treatment with anti-TNFα (infliximab, adalimumab or golimumab) or JAK-inhibitors (tofacitinib) will be initiated by clinical practice and the choice will be made at the discretion of the investigator at the center where the patients will be recruited (Hospital Universitario de La Princesa). In the case of the group of patients treated with tofacitinib, the selection will be made following the action protocol implemented in our center, in which this drug is usually reserved for those cases refractory to anti-TNFα and/or vedolizumab. There will be no random assignment of treatment. The drugs will be used in the approved indications and conditions of use.