What is the appropriate evaluation and management approach for a patient presenting with acute or chronic urticaria?

Evaluation of Urticaria

Classify urticaria by clinical presentation and duration first—acute (<6 weeks) versus chronic (≥6 weeks)—then determine if it is spontaneous or inducible, as this classification directly guides your diagnostic workup and management strategy. 1

Clinical Classification and Initial Assessment

Duration-Based Classification

• Acute urticaria lasts up to 6 weeks of continuous activity and is most common in both adults and children 1, 2
• Chronic urticaria persists for 6 weeks or more and requires a different diagnostic approach 1
• Individual wheals typically last 2–24 hours in ordinary urticaria; wheals persisting >24 hours suggest urticarial vasculitis and warrant skin biopsy 1, 3

Pattern Recognition

• Chronic spontaneous urticaria (CSU): Wheals and/or angioedema develop unprompted without definite triggers 1, 4
• Chronic inducible urticaria (CIndU): Reproducibly triggered by specific physical stimuli (cold, pressure, heat, dermographism, exercise) 1
• Physical urticaria lesions typically resolve in <1 hour, except delayed pressure urticaria which takes 2–6 hours to develop and up to 48 hours to fade 1, 3

Diagnostic Workup

Acute Urticaria

No routine investigations are required for typical acute urticaria unless the history suggests a specific trigger. 1, 5

• Diagnosis is made clinically based on history and physical examination 5, 2
• Consider IgE testing (skin prick or CAP fluoroimmunoassay) only when history suggests specific allergen triggers such as latex, nuts, or fish 1
• Extensive laboratory workups add no clinical value and should be avoided 5

Chronic Urticaria

Minimal Disease (Responsive to Antihistamines)

• No investigations required for mild chronic urticaria responding to first-line H1 antihistamines 1

Moderate-to-Severe Disease (Nonresponders)

For patients with more severe chronic urticaria not responding to standard antihistamine therapy, obtain the following screening profile: 1, 3

• Complete blood count with differential to detect eosinophilia (helminth infections) or leukopenia (systemic lupus erythematosus) 1, 3
• ESR or CRP (usually normal in chronic ordinary urticaria but elevated in urticarial vasculitis and autoinflammatory syndromes) 1, 3
• Thyroid autoantibodies with thyroid function tests (thyroid autoimmunity occurs in 14% of chronic urticaria patients versus 6% in controls) 1, 3

Additional Testing When Indicated

• Autologous serum skin test (ASST) may be performed in experienced centers to identify autoimmune chronic urticaria (approximately 30% of chronic cases) 3
• Skin biopsy when individual wheals persist >24 hours to confirm or exclude urticarial vasculitis 1, 5
• Challenge tests (cold, pressure, dermographism) to confirm specific physical urticaria subtypes 1

Red Flags Requiring Expanded Workup

If the patient presents with recurrent unexplained fever, joint/bone pain, or malaise accompanying urticaria, evaluate for autoinflammatory syndromes rather than ordinary urticaria. 1, 5

• Test for elevated inflammatory markers (CRP, ESR) and paraproteinemia in adults 1
• Look for neutrophil-rich infiltrates on skin biopsy 1
• Consider gene mutation analysis for hereditary periodic fever syndromes if strongly suspected 1

For angioedema without wheals, exclude bradykinin-mediated angioedema before diagnosing urticaria: 1

• Test complement C4, C1-INH levels and function 1
• Test for C1q and C1-INH antibodies if acquired angioedema is suspected 1
• Perform gene mutation analysis if results are unremarkable but history suggests hereditary angioedema 1
• Ask about ACE inhibitor use (remission should occur within days to 6 months of discontinuation) 1

Assessment Tools for Chronic Urticaria

At the first visit and every follow-up, assess disease activity, quality of life impairment, and disease control using validated patient-reported outcome measures. 1

• Use the 7-Day Urticaria Activity Score (UAS7) to determine disease activity and response to treatment 1
• The UAS7 ranges 0–42 and combines weekly itch severity score (0–21) and weekly hive count score (0–21) 6
• Base management decisions on disease control measurements, not just symptom presence 1

Common Pitfalls to Avoid

• Do not perform extensive laboratory testing for typical acute urticaria—it adds no value 5
• Do not assume all angioedema is histamine-mediated urticaria; bradykinin-mediated angioedema requires different management 1
• Do not overlook the prognostic significance of angioedema: in children, >50% with combined wheals + angioedema have active disease beyond 5 years, whereas ≈50% with wheals alone remit within 6 months 3
• Despite thorough evaluation, many cases remain idiopathic—this is expected and does not represent diagnostic failure 1, 3

Associations to Consider

• Helicobacter pylori: Meta-analysis shows chronic urticaria resolution is more likely when H. pylori eradication is successful 1
• Celiac disease: Significantly higher prevalence in children and adolescents with severe chronic urticaria 1
• Malignancy: No statistical association exists, though individual case reports have been published 1
• Occult infections: Little evidence supports routine investigation for dental abscess or gastrointestinal candidiasis 1