Core Dermatology Diagnoses / CategoriesInflammatory

Urticaria

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Publish date: Posted on
Last updated: October 25, 2023

Keywords #

urticaria
hives
angioedema
antihistamines

Diagnosis #

Urticaria (hives) is a common skin condition consisting of transient lesions that often burn or itch. Urticaria is a type I hypersensitivity reaction, mediated by IgE and mast cells that release histamine and vasodilatory mediators.[1] Acute urticaria is defined as outbreaks that occur recurrently for up to 6 weeks, while chronic urticaria is defined as recurrent events for longer than 6 weeks.

Because there are numerous causes of urticaria, it can be difficult to identify a specific etiology. Over 50% of cases of urticaria do not have a cause identified. Recent viral infections, medications (antibiotics, nonsteroidal anti-inflammatory drugs), and foods (shellfish, eggs, nuts) may be a cause. Urticaria often starts within minutes of exposure and maximal edema occurs within 10-15 minutes. Medications or viral infections within 2 weeks of the onset of urticaria should be considered.[2] Physical stimuli including pressure from objects, vibrations, cold, and certain contact agents (fragrance, metals) may also cause urticaria.

Key Concepts #
  • Hives are transient, pruritic or burning lesions that appear as a “wheal and flare,” with a specific lesion lasting less than 24 hours.
  • Acute urticaria is defined as waxing and waning lesions for less than 6 weeks, while chronic urticaria has lesions that arise and remit for longer than 6 weeks.
  • Most causes of urticaria are idiopathic. When a cause can be identified, infections, medications, foods, physical stimuli, and certain contact allergens are the most common agents.
  • Non-sedating antihistamines are a first-line treatment, while immunomodulating therapies are reserved for refractory cases.
Epidemiology #

It is estimated that approximately 20% of individuals will have an episode of urticaria at some point in their lives; a majority of these cases are acute urticaria, especially in childhood. Prevalence of chronic urticaria is suspected to be between 1-5% and less prevalent in children. Acute urticaria is more common to occur in individuals with a history of atopy and allergy. Approximately 10% of the population will have an episode of associated angioedema, and nearly half of individuals with chronic urticaria may experience angioedema. Angioedematous lesions result in deep swelling in the skin and are more often painful than pruritic. When angioedema occurs in the mouth or larynx it may affect breathing and require emergent care.[3]

Clinical Features #
  • Urticaria appears anywhere on the body as well-circumscribed erythematous, edematous plaques with central pallor (the classic “wheal and flare”).
  • Depending on the type of urticaria, the plaques may be round and vary in size, usually from 2 to 8 cm in diameter.[2]
  • Urticarial plaques are blanchable lesions and often quite pruritic.
  • Angioedema (including swelling of the lips and tongue) may accompany urticaria and can be a life-threatening emergency.
Differential Diagnoses #
Diagnostic Workup #

The diagnosis of hives is based on clinical appearance. There are no required laboratory tests in cases of acute urticaria unless indicated by patient history.[1] In cases of chronic urticaria, thyroid studies, basic blood work (complete blood count with differential, complete metabolic panel, and liver function tests), ANA, SSA, SSB are ordered to evaluate for chronic infection/autoimmunity and should be considered based on patient history.[4] Scratch/prick testing may also be a useful tool.

Biopsy is not usually helpful but should be performed in patients suspected of having urticarial vasculitis.

Treatment #

Non-sedating antihistamines (second generation H1 blockers such as cetirizine, loratadine, fexofenadine) are the first-line treatment and are often required in higher than standard doses. Leukotriene antagonists, such as montelukast, and sedating antihistamines (first generation H1 blockers such as diphenhydramine) can also provide additional benefit.[2] Severe cases of refractory or chronic urticaria may require immunomodulating therapies such as cyclosporine, methotrexate, PUVA, or omalizumab. Individuals who have chronic urticaria or angioedema affecting their airway should be provided an epinephrine auto-injector.[4]

Slide Viewer #
https://utahderm.med.utah.edu/image-viewer/
References #
  1. Dibbern JD, Dreskin SC. Urticaria and angioedema: an overview. Immunology and Allergy Clinics of North America. 2004;24(2):141-62.
  2. Schaefer P. Acute and chronic urticaria: evaluation and treatment. American Family Physician. 2017;95(11).
  3. Lee SJ, Ha EK, Jee HM, Lee KS, Lee SW, Kim M, Kim DH, Jung YH, Sheen YH, Sung MS, Han MY. Prevalence and risk factors of urticaria with a focus on chronic urticaria in children. Allergy, Asthma & Immunology Research. 2017;9(3):212-9.
  4. Powell R, Leech SC, Till S, Huber PA, Nasser SM, Clark AT. BSACI guideline for the management of chronic urticaria and angioedema. Clinical & Experimental Allergy. 2015;45(3):547-65.
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