What is the role of antihistamines in the treatment of chronic urticaria?

Updated: Jul 31, 2018
  • Author: Marla N Diakow, MD; Chief Editor: William D James, MD  more...
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Answer

The mainstay of pharmacotherapy for chronic urticaria is the administration of low-sedation anti-H1 antihistamines (eg, loratadine, cetirizine, levocetirizine, and fexofenadine), which have a low incidence of adverse effects. [33, 34] Quality of life appears to be improved more by daily therapy than by therapy administered on an “as needed” basis. [35]

Low-sedation antihistamines decrease the intensity of hives and pruritus in patients with mild chronic urticaria and are considered first-line therapy. Crossover studies comparing the suppression of skin papule and erythema formation induced by intradermal histamine injection after a single antihistamine dose suggest the following order of inhibitory effect: (1) levocetirizine, (2) cetirizine, (3) terfenadine, (4) fexofenadine, and (5) loratadine.

The potency of an antihistamine in inhibiting wheal and erythema formation response to intradermal histamine injection is correlated with the skin concentration of the drug rather than the plasma concentration. Sedation and impairment of performance are concerns when sedating antihistamines are used, but these adverse effects may diminish after 1-2 weeks of therapy.

Many patients find that pruritus is less troublesome during the day but is maximized at night, when there are fewer distractions. An additional nocturnal dose of a sedative antihistamine such as hydroxyzine or doxepin may be added to the morning dose of a low-sedation anti-H1 antihistamine. Doxepin should not be used in patients with glaucoma and should be used with extreme caution in elderly patients or those with heart disease.

Doubling the labeled dose of low-sedation antihistamines may benefit some patients, and increasing the dose of these antihistamines is often the safest therapeutic approach for patients who do not have an adequate response to the conventional doses of these medications. Increasing the dosage up to 4-fold is recommended by expert groups such as the European Academy of Allergy and Clinical Immunology (EAACI). [32]

As many as 75% of patients with chronic urticaria referred to tertiary care centers may require higher than conventional antihistamine doses. [36] These higher nonsedating antihistamine doses improved quality of life but did not increase somnolence. [36]

If high-dose nonsedating antihistamine therapy is not effective, switching to a different nonsedating antihistamine or adding a leukotriene antagonist (see below) to the antihistamine regimen may be considered. [32] Patients who do not respond to 20 mg of desloratadine may benefit from 20 mg of levocetirizine. [36]


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