Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT PART 6-32: REACTIVE ERYTHEMAS + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Evanescent wheals or hives Intense itching; rarely, pruritus may be absent Most episodes are acute and self-limited (1–2 weeks) Urticaria is divided into acute and chronic forms Chronic urticaria (episodes lasting longer than 6 weeks) may have an autoimmune basis +++ General Considerations ++ Urticaria may be acute (less than 6 weeks' duration) or chronic (more than 6 weeks' duration) Urticaria can result from many different stimuli on an immunologic or nonimmunologic basis Most common immunologic mechanism is mediated by IgE, which is seen in the majority of patients with acute urticaria Another involves activation of the complement cascade Cholinergic urticaria is triggered by a rise in core body temperature (hot showers, exercise) Cold urticaria is acquired or inherited and triggered by exposure to cold and wind Chronic urticaria Termed "chronic spontaneous urticaria" when there is no identifiable trigger Called chronic inducible urticaria when can be reproducibly triggered; for example Cholinergic urticaria Solar urticarias Cold urticaria Dermatographism Delayed pressure urticaria Some patients with chronic urticaria demonstrate autoantibodies directed against mast cell IgE receptors Autoimmune thyroid disease may be associated with autoimmune urticaria Acute hepatitis infection may be associated with urticarial vasculitis + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Lesions are itchy red swellings of a few millimeters to many centimeters The morphology of the lesions may vary over a period of minutes to hours Individual lesions in true urticaria last less than 24 h, and often only 2–4 h Angioedema is involvement of deeper vessels, with swelling of the lips, eyelids, palms, soles, and genitalia Angioedema is no more likely than urticaria to be associated with systemic complications such as laryngeal edema or hypotension Dermatographism Induced by scratching Can be elicited during the clinic visit by scratching the patient's skin In cholinergic urticaria, wheals are 2–3 mm in diameter with a large surrounding red flare +++ Differential Diagnosis ++ Vasculitis Erythema multiforme Contact dermatitis (eg, poison oak or ivy) Cellulitis + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Laboratory studies are not likely to be helpful in the evaluation of acute or chronic urticaria unless there are suggestive findings in the history and physical examination A complete blood count with differential, erythrocyte sedimentation rate or C-reactive protein, thyroid-stimulating hormone, and liver chemistries might be appropriate for some patients with chronic urticaria Functional ELISA test can detect patients with an autoimmune basis for their chronic urticaria +++ Diagnostic Procedures ++ In patients with individual lesions that persist past 24 h, a skin biopsy may confirm neutrophilic urticaria or urticarial vasculitis + Treatment Download Section PDF Listen +++ +++ Medications ++ H1-antihistamines Hydroxyzine, 10 mg twice daily orally to 25 mg three times daily or as a single nightly dose of 50–75 mg to reduce daytime sedation, is initial therapy Cyproheptadine, 4 mg four times daily orally, may be useful for cold urticaria Second-generation H1-antihistamines can be added if the generic sedating antihistamines are not effective Fexofenadine in a dosage of 60 mg twice daily orally or 180 mg once daily orally Loratadine or cetirizine in a dosage of 10 mg once daily orally Doxepin (a tricyclic antidepressant), 10–75 mg orally at bedtime Can be very effective in chronic urticaria Has anticholinergic side effects and is sedating H2-antihistamines in combination with H1-blockers may be helpful in patients with symptomatic dermatographism Dapsone or colchicine (or both) may be useful if neutrophils are a significant component of the inflammatory infiltrate in chronic urticaria Omalizumab Can be highly effective in refractory chronic urticaria Should be considered when severe chronic urticaria fails to respond to high-dose antihistamines Ligelizumab has been shown to be effective in early clinical trials Adjuvants Systemic corticosteroids, eg, prednisone ~40 mg once daily orally usually suppresses acute and chronic urticaria However, the use of corticosteroids is rarely indicated Cyclosporine (3–5 mg/kg/day) and other immunosuppressive medications may be effective in severe cases of chronic urticaria Topical treatment is rarely rewarding +++ Therapeutic Procedures ++ UVB phototherapy can suppress some cases of chronic urticaria + Outcome Download Section PDF Listen +++ +++ Prognosis ++ Acute urticaria usually lasts only a few days to 6 weeks 50% of patients whose urticaria persists for more than 6 weeks will have it for years Patients in whom angioedema develops during angiotensin-converting enzyme inhibitor therapy may be switched to an angiotensin receptor blocker with caution (estimated cross reactivity is about 10%) +++ When to Refer ++ There is a question about the diagnosis Recommended therapy is ineffective Specialized treatment is necessary + References Download Section PDF Listen +++ + +Antia C et al. Urticaria: a comprehensive review: epidemiology, diagnosis, and work-up. J Am Acad Dermatol. 2018 Oct;79(4):599–614. [PubMed: 30241623] + +Antia C et al. Urticaria: a comprehensive review: treatment of chronic urticaria, special populations, and disease outcomes. J Am Acad Dermatol. 2018 Oct;79(4):617–33. [PubMed: 30241624] + +Gill P et al. The clinical evaluation of angioedema. Immunol Allergy Clin North Am. 2017 Aug;37(3):449–66. [PubMed: 28687102] + +Guillén-Aguinaga S et al. Updosing nonsedating antihistamines in patients with chronic spontaneous urticaria: a systematic review and meta-analysis. Br J Dermatol. 2016 Dec;175(6):1153–65. [PubMed: 27237730] + +Larenas-Linnemann DES et al. Update on omalizumab for urticaria: what's new in the literature from mechanisms to clinic. Curr Allergy Asthma Rep. 2018 May 9;18(5):33. [PubMed: 29744661] + +Maurer M et al. Ligelizumab for chronic spontaneous urticaria. N Engl J Med. 2019 Oct 3;381(14):1321–32. [PubMed: 31577874] + +Radonjic-Hoesli S et al. Urticaria and angioedema: an update on classification and pathogenesis. Clin Rev Allergy Immunol. 2018 Feb;54(1):88–101. [PubMed: 28748365] + +Rutkowski K et al. How to manage chronic urticaria 'beyond' guidelines: a practical algorithm. Clin Exp Allergy. 2017 Jun;47(6):710–8. [PubMed: 28452145]