logo Urticaria and angioedema

Itchy skin disease

Urticaria

Objectives

  • Be able to recognise acute and chronic urticaria.
  • Outline initial treatment of urticaria.

Key points

  • Urticaria is composed of weals: recurrent transient oedematous dermal papules and plaques, individual lesions persisting less than 24 hours.
  • Weals may be asymptomatic but are often intensely itchy or sting and burn.
  • Angioedema results from oedema of dermis and subcutaneous tissue.
  • Urticaria may be acute (<6 weeks duration) or chronic (>3 months).
  • Some acute cases are due to IgE-mediated Type 1 hypersensitivity reactions.
  • Some chronic cases are due to anti-FceRI autoantibodies.
  • Angioedema may rarely be due to decreased C1-esterase inhibitor.
  • In many cases, no cause is found after careful history and investigation.
  • Allergens include: drugs (especially antibiotics), foods (eggs, milk, peanuts, shellfish).
  • Non-allergic causes include miscellaneous medical problems, infections, drugs (especially opiates, aspirin, NSAID), foods (salicylates in fruit, additives such as tartrazine, benzoates).
  • Physical urticaria may be due to light touch (dermographism), pressure, heat, cold, sweat (cholinergic), water (aquagenic), sunlight (solar) or direct contact with allergens or irritants.
  • Physical urticaria results in short-lasting weals (less than one hour).
  • Management should include avoidance of known precipitants and antihistamines.
  • Non-sedating antihistamines include loratidine, fexofenadine, cetirizine.
  • Many other medications are used in unresponsive cases including H2-blockers, ketotifen, doxepin and in acute cases for a few days, oral steroids.

Read about urticaria in your textbook or online and answer the questions.

Dermographism

Aquagenic urticaria

Acute urticaria/angioedema

Contact urticaria testing

Giant urticaria

Idiopathic chronic urticaria