Healthcare provider (HCP) participants eligible to refer patients for inclusion in this study must meet all the following criteria: 1. Have an active medical license and be board certified/board eligible allergist or dermatologist in the US. Nurse practitioners and physician assistant practicing in allergy and dermatology are eligible. 2. Manage CSU patients within their practice. 3. Enrolled in the research network or are referred HCPs who agree to participate. 4. Have the requisite patient population based on study inclusion/

. Patients eligible for inclusion in this study must meet all of the following criteria: 5. ≥ 18 years of age. 6. Diagnosed with CSU by an HCP. 7. Have received a prescription for remibrutinib or dupilumab and are expected to initiate treatment. 8. Have access to an electronic device with internet capabilities. 9. Able to read and understand English. 10. Willing and able to provide consent for study participation. Exclusion criteria: Patients will be excluded if they meet any of the following criteria: 1. Unable to procure remibrutinib or dupilumab (through samples, commercially or patient assistance program). 2. Exposure to oral corticosteroid treatment in 14 days prior to consent. 3. Exposure to oral corticosteroid treatment in 14 days prior to initiating treatment with remibrutinib or dupilumab. 4. Prior participation in a remibrutinib or dupilumab clinical trial. 5. Cognitive impairment that impacts the patient's ability to participate.