USMLE Prep - Medical Reference Library

Chronic Spontaneous Urticaria — Stepwise Therapy

System: Immunology • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Treat with high‑dose second‑generation H1 antihistamines, then omalizumab, then cyclosporine for refractory cases; avoid chronic steroids.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

For Allergy Immunology Chronic Spontaneous Urticaria, frame the differential by acuity and pathophysiology, then align diagnostics to the leading hypotheses. Prioritize stabilization while obtaining high‑yield studies such as CBC (Baseline hematology), BMP (Electrolytes/renal). Incorporate bedside imaging and targeted labs to define severity and identify complications; synthesize results with clinical trajectory to refine the working diagnosis and disposition needs.


Treatment Strategy & Disposition

Initiate disease‑directed therapy alongside supportive care, titrating to objective response. Pharmacologic options commonly include Analgesia/Antipyretics. Use validated frameworks (e.g., Stepwise Therapy) to guide escalation and site of care. Address precipitating factors, de‑escalate empiric therapies with data, and arrange follow‑up for monitoring and risk‑factor modification; admit patients with instability, high risk of deterioration, or needs for close monitoring.


Management Notes

Consider adding H2 blocker or montelukast as adjuncts in select. Track UAS7 for response.


Epidemiology / Risk Factors

  • Risk factors vary by condition and patient profile

Investigations

TestRole / RationaleTypical FindingsNotes
CBCBaseline hematologyAbnormal counts
BMPElectrolytes/renalDerangements

Stepwise Therapy

StepAction
1Standard H1 (cetirizine, fexofenadine)
2Up‑dose to 4×
3Omalizumab 300 mg q4wk
4Cyclosporine (monitor labs)
RescueShort steroid burst for flares only

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
CetirizineH1 antagonismHoursSymptomatic reliefSedation (less)
Epinephrine (if airway compromise)α/β agonistMinutesAnaphylaxis overlapArrhythmia

Prognosis / Complications

  • Prognosis depends on severity, comorbidities, and timeliness of care

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

References

  1. CSU Guideline — Link