Skin Allergy Conditions — Clinical Comparison Diagram
Atopic Dermatitis
Allergic Contact Dermatitis
Chronic Urticaria (Hives)
Irritant Contact Dermatitis
Understanding CSU
Chronic Spontaneous Urticaria (CSU) is defined as hives occurring daily or almost daily for more than six weeks without a clear external trigger. It is often an autoimmune phenomenon rather than a true allergic reaction to an external substance.
CSU affects an estimated 0.5–1% of the global population. In up to 70% of cases, no identifiable external trigger is found, hence the term "spontaneous." The underlying mechanism frequently involves autoreactive IgE antibodies or autoantibodies against FcεRI (the high-affinity IgE receptor on mast cells).
Diagnostic Criteria
Diagnosis requires a thorough history, complete blood count, thyroid function tests (to rule out thyroid autoimmunity), and relevant serology. The Urticaria Activity Score (UAS7) is used to quantify disease severity over a 7-day period and guide treatment intensity.
| Treatment Step | Therapy |
|---|---|
| First-line | Standard dose second-generation H1 antihistamines (cetirizine, loratadine) |
| Second-line | Up-dosing antihistamines (up to 4x standard dose) |
| Third-line | Omalizumab (anti-IgE biologic) — FDA approved for CSU |
| Refractory | Cyclosporine (immunosuppressant) under close monitoring |
Chronic Hives Daily Management Checklist
- Take second-generation antihistamine daily at the same time (not only when symptomatic)
- Keep a hives diary — note onset time, duration, size, and any potential triggers
- Avoid known physical triggers: heat, pressure, cold, exercise if relevant to your subtype
- Avoid aspirin/NSAIDs — can exacerbate urticaria in 30% of CSU patients
- Score your symptoms weekly using the UAS7 scale to discuss with your dermatologist or allergist
- Follow up if symptoms persist >3 months on optimal antihistamine dose — biologic therapy may be indicated