Urticaria and Angioedema

Urticaria and Angioedema is a topic covered in the Washington Manual of Medical Therapeutics.

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General Principles

Definition

  • Urticaria (hives) are raised, erythematous, well-demarcated pruritic skin lesions. Central clearing can cause an annular lesion and is often seen after antihistamine use. An individual lesion usually lasts minutes to hours.
  • Angioedema is swelling of the deep dermis and subcutaneous tissue. It is often painful rather than pruritic and generally lasts less than 48 hours. It can be found anywhere on the body but most often involves the tongue, lips, eyelids, throat, bowels, and/or genitals. When angioedema occurs without urticaria, specific diagnoses must be entertained (see Differential Diagnosis section).

Classification

  • Acute urticaria (with or without angioedema) is defined as the occurrence of hives and/or angioedema lasting <6 weeks. It can be caused by an allergic reaction to a medication, food, insect sting, or exposure (contact or inhalation) to an allergen. Patients can develop a hypersensitivity to a food, medication, or self-care product that previously had been used without difficulty. In many cases of acute urticaria, no identifiable trigger can be found.
  • Chronic urticaria (with or without angioedema) is defined as the occurrence of hives and/or angioedema for >6 weeks. There are many possible causes of chronic urticaria and angioedema, including medications, autoimmunity, self-care products, and physical triggers. However, the etiology remains unidentified in >80% of cases.

Epidemiology

  • Urticaria is a common condition that affects 15%–24% of the US population at some time in their life. Chronic idiopathic urticaria occurs in approximately 1% of the US population, and there does not appear to be an increased risk in persons with atopy.1
  • Angioedema occurs in 40%–50% of patients with urticaria.

Etiology

  • IgE-mediated: drugs, foods, stinging and biting insects, latex, inhalant, or contact allergen
  • Non–IgE-mediated: narcotics, muscle relaxants, radiocontrast, vancomycin, NSAIDs, ACE inhibitors
  • Transfusion reactions
  • Infections (i.e., viral, bacterial, parasitic)
  • Systemic disorders: autoimmune diseases, malignancy, mastocytosis, hypereosinophilic syndrome, cyroglobulinemia, and hereditary diseases
  • Physical urticaria: dermographism, cold, cholinergic, pressure, vibratory, solar, and aquagenic
  • Idiopathic

Pathophysiology

Most forms of urticaria and angioedema are caused by the degranulation of mast cells or basophils and the release of inflammatory mediators. Histamine is the primary mediator and elicits edema (wheal) and erythema (flare). Hereditary angioedema and related syndromes are mediated by the overproduction of bradykinin and are not responsive to antihistamines.

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General Principles

Definition

  • Urticaria (hives) are raised, erythematous, well-demarcated pruritic skin lesions. Central clearing can cause an annular lesion and is often seen after antihistamine use. An individual lesion usually lasts minutes to hours.
  • Angioedema is swelling of the deep dermis and subcutaneous tissue. It is often painful rather than pruritic and generally lasts less than 48 hours. It can be found anywhere on the body but most often involves the tongue, lips, eyelids, throat, bowels, and/or genitals. When angioedema occurs without urticaria, specific diagnoses must be entertained (see Differential Diagnosis section).

Classification

  • Acute urticaria (with or without angioedema) is defined as the occurrence of hives and/or angioedema lasting <6 weeks. It can be caused by an allergic reaction to a medication, food, insect sting, or exposure (contact or inhalation) to an allergen. Patients can develop a hypersensitivity to a food, medication, or self-care product that previously had been used without difficulty. In many cases of acute urticaria, no identifiable trigger can be found.
  • Chronic urticaria (with or without angioedema) is defined as the occurrence of hives and/or angioedema for >6 weeks. There are many possible causes of chronic urticaria and angioedema, including medications, autoimmunity, self-care products, and physical triggers. However, the etiology remains unidentified in >80% of cases.

Epidemiology

  • Urticaria is a common condition that affects 15%–24% of the US population at some time in their life. Chronic idiopathic urticaria occurs in approximately 1% of the US population, and there does not appear to be an increased risk in persons with atopy.1
  • Angioedema occurs in 40%–50% of patients with urticaria.

Etiology

  • IgE-mediated: drugs, foods, stinging and biting insects, latex, inhalant, or contact allergen
  • Non–IgE-mediated: narcotics, muscle relaxants, radiocontrast, vancomycin, NSAIDs, ACE inhibitors
  • Transfusion reactions
  • Infections (i.e., viral, bacterial, parasitic)
  • Systemic disorders: autoimmune diseases, malignancy, mastocytosis, hypereosinophilic syndrome, cyroglobulinemia, and hereditary diseases
  • Physical urticaria: dermographism, cold, cholinergic, pressure, vibratory, solar, and aquagenic
  • Idiopathic

Pathophysiology

Most forms of urticaria and angioedema are caused by the degranulation of mast cells or basophils and the release of inflammatory mediators. Histamine is the primary mediator and elicits edema (wheal) and erythema (flare). Hereditary angioedema and related syndromes are mediated by the overproduction of bradykinin and are not responsive to antihistamines.

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