Chronic urticaria is a common condition encountered in general practice and a frequent
source of referral to the clinical immunologist, allergist and dermatologist.
This article discusses the assessment and management of chronic urticaria in the
general practice setting.
Chronic urticaria is defined as the occurrence of transient wheals lasting more than
6 weeks in duration. In 80% of cases, a cause is not identified and this is classified
as chronic idiopathic urticaria. A physical trigger, vasculitis or systemic disease
account for a smaller proportion of cases. Allergic causes are rarely responsible. A
detailed history provides the most useful information in determining the presence
of chronic urticaria and a possible aetiology. Apart from thyroid function tests and
thyroid autoantibodies, other investigations should only be performed if clinically
indicated. Second generation antihistamines are the mainstay of treatment and usually
twice daily regimens are required for adequate control. H2 antagonists, doxepin and
immunomodulation may be necessary in some patients.
Urticaria is characterised by the rapid appearance of transient, pruritic skin swellings (wheals) of variable size surrounded by reflex erythema lasting less than 24 hours and leaving no residual skin changes (Figure 1). Urticaria is a common condition, affecting up to 20% of the population.1 It is broadly classified into acute and chronic forms. Acute urticaria is defined as episodes of less than 6 weeks duration and accounts for over two-thirds of cases. An allergic or infectious trigger is sometimes identified (Table 1). Chronic urticaria (CU) is defined as episodes extending beyond 6 weeks and accounts for 30% of cases.
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