Overview of CSU

CSU accounts for approximately 80% of chronic urticaria cases, with the remaining 20% being inducible forms. The hallmark symptom of CSU is the appearance of itchy, red, raised lesions (or hives) that resolve spontaneously within hours, leaving no scars or skin texture changes. Approximately half of patients with CSU also experience angioedema, typically presenting as asymmetrical, nonitchy soft tissue swelling. This distinguishes CSU from many other skin conditions, which are more persistent or show different inflammatory patterns.

The most notable comorbid condition associated with CSU is autoimmune thyroid disease. Up to a third of patients may test positive for thyroid autoantibodies, even if they are euthyroid, suggesting an underlying immune dysregulation. This comorbidity is more common in CSU than in many other skin conditions. Differentiating CSU from conditions like eczema, poison ivy, or flushing disorders relies heavily on the fleeting nature of CSU hives, which contrasts with the fixed, persistent lesions seen in most other dermatologic diseases.

In terms of patient journey, individuals with CSU typically develop symptoms suddenly, often without prior warning. Many first seek treatment at urgent care or emergency departments, where they may receive antihistamines or steroids. When symptoms persist daily, as is characteristic of CSU, patients are often referred to primary care, dermatology, or allergy specialists. Increasing awareness among both patients and providers has helped reduce delays in diagnosis, leading to earlier intervention, evaluation for underlying causes, and initiation of appropriate long-term treatment plans.