Chronic spontaneous urticaria (CSU), chronic, unexplained hives, affects an estimated 1–3% of adults. For those affected, CSU can be a profoundly disruptive condition causing significant itching, sleep disturbance, anxiety, and quality of life impairment on par with coronary artery disease.
What Is CSU?
Urticaria refers to hives, raised, red, itchy welts on the skin. When hives appear spontaneously (without an identifiable external trigger) and persist for 6 weeks or longer, the condition is classified as chronic spontaneous urticaria.
CSU is distinct from acute urticaria (resolves within 6 weeks) and chronic inducible urticaria (consistently triggered by a physical stimulus like cold or pressure).
What Causes CSU?
In most patients, no specific trigger can be identified despite extensive investigation. Research suggests autoimmune mechanisms play a central role, approximately 40–50% of CSU patients have autoantibodies that activate mast cells in the skin, causing histamine release and hive formation.
Symptoms
- Wheals (raised welts) that appear and disappear over hours, individual lesions typically last less than 24 hours
- Intense itching, often worse at night
- Angioedema, deep swelling of the face, lips, throat, or hands, occurs in about 40% of CSU patients
- No consistent external trigger
Treatment
Second-generation antihistamines (cetirizine, fexofenadine, loratadine) are first-line treatment. Many patients require higher-than-standard doses.
Omalizumab (Xolair), a biologic targeting IgE, is highly effective for patients who do not respond to antihistamines and is FDA-approved for CSU.
Emerging biologics, additional therapies are in clinical trials for CSU patients who remain symptomatic on omalizumab.
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