Urticaria is a cutaneous syndrome characterized by dermal
edema (wheal) and
erythema (flare) that blanches with pressure. The lesions typically last less than 24 hours and are usually pruritic. In 1983, Christensen and Maibach summarized the theory behind the use of
histamine H1 receptor antagonists (
antihistamines) in clinical dermatology. These agents remain the mainstay of treatment for
urticaria. This article reviews the medical literature on the effectiveness of
antihistamines in urticarial syndromes, including acute, chronic idiopathic and the physical
urticarias. Older
antihistamines, such as
chlorpheniramine and
hydroxyzine, are effective in the treatment of
urticarias, but they also have marked
sedative and
anticholinergic effects. Newer nonsedating
antihistamines (second-generation antihistamines) have been developed that have reduced adverse effects because they do not cross the blood-brain barrier; these agents (
acrivastine,
cetirizine,
loratadine,
mizolastine,
fexofenadine,
ebastine,
azelastine and
epinastine) cause significantly less sedation and
psychomotor impairment than their older counterparts. A review of the literature reveals that there are few studies which document the efficacy of
second-generation antihistamines in the treatment of acute
urticaria, a
biologic entity that usually resolves within 3 weeks. We did not identify controlled studies that suggested superiority of any
antihistamine in the treatment of acute
urticaria.
Loratadine or
cetirizine, and possibly
mizolastine, appear to be treatments of choice for
chronic idiopathic urticaria. For symptomatic dermatographism, the combination of an
antihistamine and an H2 antagonist, e.g.
chlorpheniramine and
cimetidine, appears to be effective. Very few studies have been conducted on the use of
antihistamines in the treatment of cold,
cholinergic, and pressure
urticaria.
Antihistamines are the mainstay of urticarial
therapy. This evidence-based review suggests that there are efficacy differences between newer, nonsedating
antihistamines and older agents in some forms of the disorder. Clearly, further well-controlled clinical trials in larger numbers of patients are needed to clarify the role of these agents in the treatment of
urticaria.