Urticaria & Angioedema

1. Definition

Neither urticaria nor angioedema are diagnoses. Both are symptoms and signs in the skin.

Urticaria consists of multiple erythematous, blanching papules or “wheals”. Wheals comprise a central oedematous, compressible, non-scaling, flat topped and palpable swelling, almost invariably surrounded by erythema (flares). Wheals are polymorphous, varing in size from 1 mm to many centimetres.. Urticaria is itchy but not painful.

Angioedema is an episodic, transient deeper swelling within the deep tissues or subcutaneous layers of the skin and mucous membranes

2. Introduction

Urticaria and angioedema are common reasons for allergy consultations. Urticaria may have significant effects on quality of life, restricting normal daily activities, reducing sleep, causing social isolation and emotional distress. Most urticaria is spontaneous with no trigger factors identifiable. Forty percent of chronic spontaneous urticaria is now thought to be autoimmune.

3. Causes

3.1. Acute urticaria

  • IgE mediated reactions
  • Viral infections
  • Direct histamine release
  • Exogenous histamine
  • Papular urticaria
  • Drug related urticaria
  • Contact urticaria
  • Infections
  • Medical conditions
  • Hormone related
  • Stress related

3.2. Chronic inducible urticaria

Inducible uticaria results in reproducible whealing in response to a specific physical stimulus. Triggers include cold, heat, sweating, exercise, sunlight, water, pressure and vibration. The wheals of inducible urticaria tend to be short-lived (less than 1 hour) apart from those of delayed pressure urticaria.

  • Cold urticaria (acquired cold urticaria)
  • Cholinergic urticaria
  • Delayed pressure urticaria
  • Solar urticaria
  • Aquagenic urticaria
  • Vibration


4.1. Non-drug treatment

Aims of treatment are to increase quality of life.

  • Physical (reduce itch and pain)
  • Emotional (allow normalisation of self image and relationships)
  • Reduce restriction of activities (sport and self care)
  • Remove restrictions on school or work
  • Limit side effects of medication

An exact diagnosis is a prerequisite. The following refers to spontaneous chronic or acute urticaria. Specific treatment is necessary for urticarial syndromes, angioedema without urticaria and masqueraders of urticaria. When necessary, efforts must be made to identify specific causes and triggers.

4.2. Drug treatment

Antihistamines are the mainstay of treatment for urticaria. Topical antihistamines are ineffective. If symptoms are infrequent, as required treatment with antihistamines may be used. Many patients require the regular use of oral antihistamines. Sedating antihistamines (promethazine, diphenhydramine, chlorpheniramine and hydroxyzine) should be avoided as first line agents except in the rare cases where they prove to be better tolerated or more effective than non-sedating antihistamines. Second generation antihistamines (cetirizine, levocetirizine, loratadine, desloratadine, fexofenadine, acrivastine, ebastine, rupatadine and mizolastine) are minimally sedating and free of anticholinergic side effects.

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