Urticaria
Classification and main causes
- Acute urticaria (< 6 weeks): IgE-mediated allergy (foods—peanuts + seafood + egg + milk + fish + nuts + latex + medications—penicillin + NSAIDs + aspirin + insect venom) + viral infection (most common in children—RSV + rhinovirus + EBV + HCV) + pseudoallergic reaction (colorants + food preservatives + NSAIDs—non-IgE-mediated reaction by direct mast cell activation) + idiopathic in 30–40 % of cases
- Chronic spontaneous urticaria (CSU - > 6 weeks): idiopathic or autoimmune (IgG autoantibodies anti-IgE or anti-FcεRI → direct mast cell activation) + associations: chronic infections (H. pylori + parasitic infections + infectious foci) + autoimmune diseases (Hashimoto's + lupus + 20 % with Urticaria Chronic Spontaneous) + neoplasms (rare) + stress + in 75–85 % of cases: no identifiable cause despite workup
- Inducible urticarias (triggered by a physical stimulus): Dermographic urticaria (friction) + cold urticaria (contact with cold → possible anaphylaxis if swimming in cold water) + solar urticaria (UVA + UVB) + cholinergic urticaria (exercise + sweat + heat + stress — characteristic small punctate papules) + pressure urticaria + vibratory urticaria + aquagenic urticaria
- Hereditary Angioedema (HAE) — to be distinguished from hives: C1-inhibitor deficiency (quantitative or functional) + or kallikrein dysfunction (HAE type III) → bradykinin-dependent edema → NON-histaminergic → resistant to antihistamines and corticosteroids → specific treatment (icatibant + C1-inhibitor concentrate) → see hereditary angioedema sheet
Tiered treatment
| Bearing | Treatment | Dosage and Remarks |
|---|---|---|
| Level 1 — 2nd Generation H1 Antihistamines (Non-sedating) — First-line | Cetirizine (Reactine®) + loratadine (Claritin®) + fexofenadine (Allegra®) + bilastine + desloratadine | Cetirizine 10 mg/day + loratadine 10 mg/day + fexofenadine 180 mg/day → continuous treatment (not just as needed) + 1 tablet/day + safe + non-sedating + no anticholinergic effect + effective on itching and lesions |
| Stage 2 — Increase dose of HA1 (up to 4x) | Cetirizine up to 40 mg/day or loratadine 40 mg/day or fexofenadine 360–720 mg/day | Quadrupling the standard dose → improvement in 40–60 % of UCS refractory to step 1 + off-label but recommended EAACI 2022 + before moving to higher steps |
| Stage 3 — Omalizumab (anti-IgE) — refractory chronic urticaria | Omalizumab (Xolair®) 300 mg SC every 4 weeks | Health Canada + FDA approval for refractory UC + 60-70% % complete control efficacy + rapid response (1-2 weeks) + well-tolerated + 6-month to 1-year treatment + possible prolonged remission after discontinuation |
| Level 4 — Cyclosporine (severe refractory cases) | Cyclosporine 2.5–5 mg/kg/day × 3–6 months | Inhibits mast cell degranulation + effective in autoimmune UCTDs + adverse effects: nephrotoxicity + hypertension + infections + mandatory biological monitoring + reserved for very severe cases refractory to omalizumab |
| Corticosteroids (limited use) | Prednisone 0.5 mg/kg/day × 5–7 days (severe acute urticaria or flare) | Effective for acute flare-ups + but DO NOT use for maintenance treatment of IBD (adverse effects long-term + rebound upon discontinuation) + reserved for severe flare-ups or anaphylaxis |
Acute Urticaria — Assessment and Management
- Oriented anamnesis: Delay between exposure and onset of lesions + foods ingested within 2 hours + medications (NSAIDs + penicillin + ACE inhibitors) + insect bites + contact (latex + cosmetics) + recent infections + physical activity + stress + personal and family history of atopy
- Minimal assessment (acute isolated urticaria): Often no workup is needed if the cause is obvious (food + medication). If recurrent or the cause is not obvious, then CBC + CRP + total IgE + TSH + H. pylori serology + liver function tests.
- Allergy testing: Prick tests + dosage of specific IgE → if IgE-mediated allergy is suspected + within 4–6 weeks after recovery (tests may be negative during an acute episode)
- Epinephrine (adrenaline) auto-injector: Prescribe an epinephrine auto-injector (EpiPen® + Allerject®) if severe acute urticaria with anaphylactic risk, or severe anterior angioedema, or confirmed severe food allergy → patient education on its use
Chronic spontaneous urticaria — reasoned evaluation
- Recommended basic assessment (EAACI 2022): NFS + VS + CRP + TSH + anti-TPO (Hashimoto - frequent association) + H. pylori serology → search for a treatable cause
- Extended assessment (if indicative symptoms) : Liver function tests + HBV serology + HCV serology + antinuclear antibodies + complement C3 + C4 + C1 inhibitor (recurrent angioedema) + specific IgE if food allergy suspected + stool parasitology (eosinophilia)
- U UAS7 (Urticaria Activity Score 7 days): validated tool to assess the severity and monitor the evolution of CSU → score from 0 to 42 based on the number of lesions + the intensity of pruritus over 7 consecutive days → UAS7 > 28 = severe urticaria
Call 911 immediately if hives are accompanied by throat swelling + difficulty swallowing or breathing + hoarse voice + low blood pressure + rapid heartbeat + or loss of consciousness — these signs indicate anaphylaxis or laryngeal angioedema requiring immediate intramuscular injection of epinephrine (EpiPen®) + then call 911. Anyone who has previously experienced an anaphylactic reaction must carry an epinephrine auto-injector with them at all times. For the treatment of chronic hives and the prescription of omalizumab, Clinique Omicron offers medical consultations at its service points in Quebec and through telemedicine. To make an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's physicians and nurse practitioners diagnose and treat acute and chronic urticaria, initiate standard dose second-generation H1 antihistamines, increasing to quadrupled doses if necessary, prescribe etiological workups based on the clinical context, refer to allergology for allergen testing and desensitization, prescribe epinephrine auto-injectors to patients at risk of anaphylaxis, and refer to dermatology or immunology for the initiation of omalizumab in refractory CSU. Consultations are available at several service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not replace the advice of a doctor or an allergist-dermatologist. Laryngeal angioedema is a life-threatening emergency—inject the auto-injectable adrenaline immediately and call 911. Hereditary angioedema (C1 inhibitor deficiency) does not respond to antihistamines or corticosteroids—it requires specific treatment with icatibant or C1 inhibitor concentrate.
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