Urticaria is a common mast cell–mediated dermatologic condition characterized by pruritic, erythematous, raised wheals that individually resolve within 24 hours. It is classified as acute (<6 weeks) or chronic (≥6 weeks), with 80–90% of chronic cases being idiopathic. [1] The primary mechanism is histamine release from dermal mast cells, most commonly via IgE-mediated type 1 hypersensitivity. [1]
The following diagnostic algorithm provides a useful framework for evaluating urticarial presentations:
1. History
- Onset and timing: Acute (<6 weeks) vs. chronic (≥6 weeks); continuous vs. episodic; time of day; relationship to activities [1][3]
- Characterization of lesions: Size, shape, distribution, blanching, duration of individual wheals (<24 hours is typical; >24 hours suggests vasculitis) [1][4]
- Triggers: Foods (nuts, shellfish, eggs, dairy), medications, insect stings, infections, physical stimuli (cold, heat, pressure, exercise), stress, latex, aeroallergens [1][3]
- Temporal relationship: Food ingestion within 2 hours, new medication within days to weeks, recent infection [3][5]
- Associated symptoms: Angioedema (lip/tongue/eyelid swelling), pruritus severity, burning vs. itching quality [1]
- Important negatives: Absence of dyspnea, wheezing, stridor, lightheadedness, abdominal pain, vomiting, diarrhea, syncope (rules out anaphylaxis) [3]
- Review patient photographs of lesions if not present at time of evaluation [1][6]
2. Alarm Features
- Anaphylaxis signs: Hypotension, tachycardia, bronchospasm, stridor, laryngeal edema, abdominal pain, vomiting, diarrhea, dizziness, loss of consciousness [1][3]
- Urticarial vasculitis: Wheals lasting >24 hours, burning pain (not itch), residual ecchymosis/hyperpigmentation, fever, arthralgias [1][4]
- Systemic disease clues: Fevers, night sweats, unintentional weight loss (lymphoma); joint pain, uveitis (autoimmune disease) [1]
- Angioedema without wheals: Consider bradykinin-mediated angioedema (ACE inhibitor–induced or hereditary angioedema) — antihistamines are ineffective in these cases [1][7]
- Epinephrine should be prescribed if anaphylaxis has not been excluded [3]
3. Medications
Common culprits/exacerbators:
- NSAIDs — can induce or exacerbate urticaria via prostaglandin E2 suppression; present in up to 30% of chronic urticaria exacerbations. Recommend acetaminophen as alternative analgesic/antipyretic [1][8-9]
- ACE inhibitors — associated with bradykinin-mediated angioedema (not histamine-mediated); discontinue and observe for 6 weeks [1][3]
- β-lactam antibiotics — most common drug-induced urticaria trigger in children [5]
- Opioids, vancomycin — direct mast cell degranulation (non-IgE mediated) [1]
- Aspirin — cross-reactivity with NSAID-exacerbated urticaria
Treatments:
- First-line: Second-generation H1 antihistamines (cetirizine, loratadine, fexofenadine, levocetirizine) [1]
- Refractory acute: Short course oral corticosteroids (prednisone 40–50 mg × 3–5 days), though evidence of benefit is conflicting [3][10]
- Chronic refractory: Omalizumab (Xolair) 300 mg SC q4 weeks for antihistamine-resistant chronic spontaneous urticaria [6][11]
Contraindicated/avoid:
- Topical antihistamines and topical corticosteroids — not effective [1]
- Long-term systemic corticosteroids for chronic urticaria [1]
4. Diet
- Acute urticaria: Nuts, shellfish, eggs, cow's milk, and fish are the most common IgE-mediated food triggers [5][12]
- Histamine-rich foods may exacerbate symptoms: aged cheese, preserved/cured meats, improperly stored fish (scombroid), fermented foods, alcohol [1]
- Pseudoallergens: Food additives (tartrazine dye, benzoates, salicylates) may trigger non-IgE–mediated reactions [1][7]
- Empiric elimination diets are NOT recommended unless guided by specific history and testing [3]
- Adequate hydration is supportive but not specifically evidence-based for urticaria
- Diets rich in omega-3 fatty acids, legumes, nuts, and whole grains may have a protective association [13]
5. Review of Systems
- Pulmonary: Dyspnea, wheezing, cough, stridor (anaphylaxis, angioedema)
- GI: Abdominal pain, nausea, vomiting, diarrhea (anaphylaxis, food allergy)
- Cardiovascular: Lightheadedness, syncope, palpitations (anaphylaxis)
- ENT: Lip/tongue/throat swelling, voice change, dysphagia (angioedema)
- Musculoskeletal: Joint pain, swelling (autoimmune disease, serum sickness, urticarial vasculitis)
- Constitutional: Fevers, night sweats, weight loss (lymphoma, infection, autoinflammatory syndromes) [1]
- Endocrine: Cold intolerance, weight gain, fatigue (hypothyroidism) [1]
- Dermatologic: Lesion duration, burning vs. itching, residual skin changes [1][4]
6. Collateral History and Family History
- Family history of urticaria or atopy (asthma, eczema, allergic rhinitis) [1]
- Hereditary angioedema (HAE types 1–3): Family history of recurrent angioedema without urticaria, autosomal dominant [7]
- Cryopyrin-associated periodic syndromes (CAPS): Familial cold autoinflammatory syndrome, Muckle-Wells syndrome [7]
- Social context: Occupational exposures (latex, chemicals), travel history (parasitic infections), sexual history and substance use (hepatitis B/C, HIV risk) [1][3]
- Transfusion history — risk for hepatitis-associated urticaria [3]
7. Risk Factors
- Female sex — higher prevalence, especially for chronic spontaneous urticaria [6][13]
- Atopic history — asthma, allergic rhinitis, eczema
- Infections: Viral URIs (most common trigger in children, up to 23%), UTIs, GI infections, H. pylori [1][5]
- Autoimmune disease: Autoimmune thyroiditis, SLE, Sjögren syndrome, rheumatoid arthritis, celiac disease [1]
- Medication use: NSAIDs, ACE inhibitors, antibiotics, opioids [1][6]
- Stress — reported trigger in ~14% of chronic urticaria patients [6]
- Environmental: Air pollution (ozone, particulate matter) positively correlated with urticaria incidence [13]
- Younger age groups carry higher disease burden globally [13]
8. Differential Diagnosis
- Anaphylaxis — urticaria + systemic symptoms (hypotension, bronchospasm, GI symptoms); must be excluded in every ED presentation [3]
- Urticarial vasculitis — wheals >24 hours, burning pain, ecchymosis, residual hyperpigmentation; biopsy shows leukocytoclastic vasculitis [4][8]
- Erythema multiforme — target lesions, fixed (not migratory), often post-infectious (HSV) or drug-related
- Bullous pemphigoid — urticarial prodrome may precede blistering; older adults [8]
- Contact dermatitis — localized, distribution matches exposure
- Drug eruption — morbilliform rash, fixed drug eruption; temporal relationship to medication
- Serum sickness–like reaction — urticaria + fever + arthralgias, typically 1–3 weeks after drug exposure (cefaclor, amoxicillin)
- Hereditary angioedema — recurrent angioedema WITHOUT wheals; does not respond to antihistamines [7]
- Mastocytosis/systemic mastocytosis — urticaria pigmentosa, Darier sign [1]
- Autoinflammatory syndromes: Schnitzler syndrome (urticaria + monoclonal gammopathy), CAPS [7]
- Stevens-Johnson syndrome/TEN — painful, non-pruritic, mucosal involvement (cannot-miss) [2]
9. Past Medical History
- Prior episodes of urticaria or angioedema and identified triggers
- History of atopy (asthma, allergic rhinitis, eczema)
- Autoimmune thyroid disease — most common autoimmune comorbidity [1][6]
- Prior anaphylaxis and epinephrine auto-injector use
- Chronic infections (hepatitis B/C, HIV, H. pylori) [1]
- Surgical history (implants, transfusions)
- Pregnancy — pruritic urticarial papules and plaques of pregnancy (PUPPP) [1]
10. Physical Exam
- Vital signs: Tachycardia, hypotension, tachypnea → concern for anaphylaxis [3]
- Skin: Characterize wheals — raised, erythematous, blanching, well-circumscribed; note distribution, size, confluence; check for ecchymosis or residual pigmentation (vasculitis) [1][3]
- Dermatographism testing: Stroke skin with blunt end of tongue blade; positive = linear wheal at site of pressure [1]
- Angioedema: Examine lips, tongue, periorbital area, hands, feet, genitalia for deep tissue swelling [3]
- HEENT: Oropharyngeal edema, stridor, voice changes (airway compromise) [3]
- Lungs: Wheezing, decreased air entry
- Abdomen: Tenderness (visceral angioedema)
- Lymph nodes/thyroid: Lymphadenopathy (lymphoma), thyromegaly (hypothyroidism) [1][3]
- Musculoskeletal: Joint swelling/tenderness (autoimmune, vasculitis)
11. Lab Studies
Acute urticaria: Diagnostic testing is typically not required [1]
If clinically indicated (recurrent or atypical):
- CBC with differential (eosinophilia → allergic/parasitic; basopenia → autoimmune CSU) [3][6]
- ESR and/or CRP (elevated → vasculitis, infection, autoimmune) [1][6]
Chronic urticaria workup:
- CBC with differential, ESR, CRP [1]
- Total IgE [1]
- TSH and anti-thyroid peroxidase (anti-TPO) IgG [1][6]
- Consider: hepatitis B/C serologies, HIV, H. pylori testing if history suggests [1][6]
- Complement levels (C3, C4, CH50) if urticarial vasculitis or hereditary angioedema suspected [1][4]
- Tryptase — if mastocytosis or anaphylaxis suspected
Intensive and costly general screening programs are strongly advised against [6-7]
12. Imaging
- Imaging is generally NOT indicated for uncomplicated urticaria
- Consider chest X-ray if respiratory symptoms present to evaluate for alternative diagnoses
- CT neck/soft tissue if concern for airway-compromising angioedema not responding to treatment
- Imaging for underlying malignancy only if constitutional symptoms (weight loss, night sweats, fevers) are present [1]
13. Special Tests
- Urticaria Activity Score (UAS7): Patient-reported daily wheal count and itch severity over 7 days; useful for monitoring chronic urticaria [1][6]
- Urticaria Control Test (UCT): 4-item questionnaire to assess disease control; guides step-up therapy decisions [6]
- Skin-prick testing: For suspected IgE-mediated food or venom allergy; perform after acute episode resolves and antihistamines are held [3]
- Serum-specific IgE: Alternative to skin-prick testing, especially with dermatographism [3]
- Autologous serum skin test (ASST): Screens for autoimmune urticaria (functional autoantibodies) [1]
- Basophil activation test / basophil histamine release assay: Identifies autoimmune CSU [6]
- Skin biopsy: Indicated if wheals last >24 hours, are painful/burning, leave ecchymosis, or vasculitis is suspected [1][4]
- Physical provocation testing: Ice cube test (cold urticaria), exercise challenge (cholinergic), pressure test (delayed pressure urticaria) [7]
14. ECG
- Not routinely indicated for uncomplicated urticaria
- Obtain ECG if:
- Anaphylaxis is suspected (Kounis syndrome — allergic coronary vasospasm)
- Hemodynamic instability or chest pain
- Pre-existing cardiac disease with epinephrine administration
- Patterns to recognize: Sinus tachycardia (anaphylaxis), ST changes (Kounis syndrome), arrhythmias in setting of epinephrine use
15. Assessment
- Acute urticaria is self-limited in most cases; the most common cause in children is viral infection [3][5]
- Chronic spontaneous urticaria is idiopathic in 80–90% of cases; remission occurs in ~50% within 1–5 years [1][9]
- Severity stratification: Isolated wheals (mild) → widespread wheals with angioedema (moderate) → systemic symptoms/anaphylaxis (severe) [3]
- Atypical features warranting further workup: wheals >24 hours, burning pain, residual hyperpigmentation, systemic symptoms, isolated angioedema without wheals [1][4][8]
- Complications: Anaphylaxis, airway compromise from angioedema, significant quality-of-life impairment, sleep disruption, psychological distress [1][9]
16. Treatment Plan
Acute Urticaria — ED/Urgent Care:
- First-line: Second-generation H1 antihistamine (e.g., cetirizine 10 mg PO, fexofenadine 180 mg PO) [1][14]
- If IV needed in ED: IV second-generation antihistamine preferred over first-generation (lower return-to-ED rate, fewer adverse events) [14]
- Refractory to antihistamines: Consider short course oral prednisone 40–50 mg/day × 3–5 days, though evidence of benefit is conflicting and one RCT found no benefit of adding IV dexamethasone. Continue antihistamines during and after steroid course [1][3][10]
- If anaphylaxis suspected: IM epinephrine 0.3–0.5 mg (1:1000) into anterolateral thigh; repeat q5–15 min as needed [3]
- Prescribe epinephrine auto-injector if anaphylaxis cannot be excluded [3]
Chronic Urticaria — Stepped Approach:
- Step 1: Second-generation H1 antihistamine at standard dose (daily, not PRN) [3][9]
- Step 2: Increase dose up to 4× standard dose (e.g., cetirizine 10 mg QID) — FDA-approved, minimal additional adverse effects [1][6][9]
- Step 3: Add leukotriene receptor antagonist (montelukast) or H2 blocker (evidence is conflicting); consider hydroxyzine or doxepin at bedtime [1][3]
- Step 4: Omalizumab 300 mg SC q4 weeks for antihistamine-refractory CSU [6][11]
- Step 5: Cyclosporine 3 mg/kg/day (off-label) for omalizumab-refractory cases; requires BP and renal monitoring [6]
- Avoid long-term systemic corticosteroids for chronic urticaria [1]
Non-pharmacologic: Avoid known triggers, NSAIDs, tight clothing, excessive heat, alcohol, stress [3][9]
17. Disposition
Admission criteria:
- Anaphylaxis requiring epinephrine or hemodynamic support
- Airway-compromising angioedema (laryngeal, oropharyngeal)
- Refractory symptoms despite ED treatment with ongoing systemic symptoms
- Concern for serious underlying etiology (vasculitis with systemic involvement, serum sickness)
Observation:
- Post-anaphylaxis observation for 4–6 hours minimum (biphasic reaction risk)
- Angioedema involving face/neck with good response to treatment — observe for rebound
Discharge criteria:
- Isolated urticaria without systemic symptoms
- Symptoms improving with antihistamines
- Able to tolerate oral medications
- No airway involvement
Specialist consultation triggers:
- Wheals lasting >24 hours with residual hyperpigmentation → dermatology/allergy (biopsy for vasculitis) [6]
- Antihistamine-refractory chronic urticaria → allergy/immunology [6]
- Isolated angioedema without wheals → allergy (rule out HAE) [7]
- Extracutaneous symptoms (fever, arthralgias, abdominal pain) → allergy/rheumatology [6]
18. Follow Up / Return Precautions
Follow-up timing:
- Acute urticaria: PCP follow-up within 1–2 weeks if symptoms persist; most cases resolve spontaneously [1][3]
- If approaching 6 weeks of symptoms → initiate chronic urticaria workup [3]
- Chronic urticaria: Regular follow-up q4–8 weeks to titrate therapy and assess disease control (UCT score) [6]
Return precautions — seek immediate care for:
- Difficulty breathing, throat tightness, voice changes, tongue/lip swelling
- Lightheadedness, dizziness, fainting
- Abdominal pain, vomiting, diarrhea with hives
- Rapid spread of hives with worsening symptoms despite antihistamines
Patient counseling:
- Urticaria is common and usually self-limited; most acute cases resolve within days to weeks [1]
- Take antihistamines daily (not PRN) for best control [9]
- Avoid NSAIDs (use acetaminophen instead), alcohol, and known triggers [6][9]
- Photograph lesions when they appear — transient nature makes clinic evaluation challenging [1][6]
- Chronic urticaria may wax and wane; ~50% achieve remission within 1–5 years [9]
References
1. Acute and Chronic Urticaria: Evaluation and Treatment. — Semenya AM, Pienkowski S, Bhatnagar P. American Family Physician. 2026.
2. Acute and Chronic Urticaria: Evaluation and Treatment. — Semenya AM, Pienkowski S, Bhatnagar P. American Family Physician. 2026.
3. Acute and Chronic Urticaria: Evaluation and Treatment. — Semenya AM, Pienkowski S, Bhatnagar P. American Family Physician. 2026.
4. Urticaria. — Gary Foley Clinical Guide to Paediatrics. 2022.
5. Urticaria. — Gary Foley Clinical Guide to Paediatrics. 2022.
6. The Diagnosis and Management of Acute and Chronic Urticaria: 2014 Update. — Bernstein JA, Lang DM, Khan DA, et al. The Journal of Allergy and Clinical Immunology. 2014.
7. The Diagnosis and Management of Acute and Chronic Urticaria: 2014 Update. — Bernstein JA, Lang DM, Khan DA, et al. The Journal of Allergy and Clinical Immunology. 2014.
8. Urticarial Vasculitis: Clinical and Laboratory Findings With a Particular Emphasis on Differential Diagnosis. — Marzano AV, Maronese CA, Genovese G, et al. The Journal of Allergy and Clinical Immunology. 2022.
9. Urticarial Vasculitis: Clinical and Laboratory Findings With a Particular Emphasis on Differential Diagnosis. — Marzano AV, Maronese CA, Genovese G, et al. The Journal of Allergy and Clinical Immunology. 2022.
10. The common triggers of urticaria in children admitted to the pediatric emergency room. — Bezirganoglu H, Arik Yilmaz E, Sahiner UM, et al. Pediatric Dermatology. 2022.
11. The common triggers of urticaria in children admitted to the pediatric emergency room. — Bezirganoglu H, Arik Yilmaz E, Sahiner UM, et al. Pediatric Dermatology. 2022.
12. Chronic Spontaneous Urticaria: A Review. — Kolkhir P, Bonnekoh H, Metz M, Maurer M. The Journal of the American Medical Association. 2024.
13. Chronic Spontaneous Urticaria: A Review. — Kolkhir P, Bonnekoh H, Metz M, Maurer M. The Journal of the American Medical Association. 2024.
14. The EAACI/GA²LEN/EDF/WAO Guideline for the Definition, Classification, Diagnosis and Management of Urticaria. — Zuberbier T, Aberer W, Asero R, et al. Allergy. 2018.
15. The EAACI/GA²LEN/EDF/WAO Guideline for the Definition, Classification, Diagnosis and Management of Urticaria. — Zuberbier T, Aberer W, Asero R, et al. Allergy. 2018.
16. Chronic Spontaneous Urticaria. — Yosipovitch G, Maderal AD, Elman SA. JAMA Dermatology. 2025.
17. Chronic Spontaneous Urticaria. — Yosipovitch G, Maderal AD, Elman SA. JAMA Dermatology. 2025.
18. Chronic Urticaria. — Lang DM. The New England Journal of Medicine. 2022.
19. Chronic Urticaria. — Lang DM. The New England Journal of Medicine. 2022.
20. A Randomized Controlled Trial of Adding Intravenous Corticosteroids to H1 Antihistamines in Patients With Acute Urticaria. — Palungwachira P, Vilaisri K, Musikatavorn K, Wongpiyabovorn J. The American Journal of Emergency Medicine. 2021.
21. A Randomized Controlled Trial of Adding Intravenous Corticosteroids to H1 Antihistamines in Patients With Acute Urticaria. — Palungwachira P, Vilaisri K, Musikatavorn K, Wongpiyabovorn J. The American Journal of Emergency Medicine. 2021.
22. FDA Orange Book. — FDA Orange Book. 2026.
23. FDA Orange Book. — FDA Orange Book. 2026.
24. Nutrition and Urticaria. — Shao K, Feng H. Clinics in Dermatology. 2021.
25. Nutrition and Urticaria. — Shao K, Feng H. Clinics in Dermatology. 2021.
26. Global, Regional, and National Burden of Urticaria (1990-2021), Its Potential Risk Factors, and Projections to 2046. — Tan S, Chen Z, Lin T. BMC Public Health. 2025.
27. Global, Regional, and National Burden of Urticaria (1990-2021), Its Potential Risk Factors, and Projections to 2046. — Tan S, Chen Z, Lin T. BMC Public Health. 2025.
28. Evaluation of Pharmacological Treatments for Acute Urticaria: A Systematic Review and Meta-Analysis. — Jamjanya S, Danpanichkul P, Ongsupankul S, et al. The Journal of Allergy and Clinical Immunology. In Practice. 2024.
29. Evaluation of Pharmacological Treatments for Acute Urticaria: A Systematic Review and Meta-Analysis. — Jamjanya S, Danpanichkul P, Ongsupankul S, et al. The Journal of Allergy and Clinical Immunology. In Practice. 2024.