Acute and chronic urticaria are treated with antihistamines. Use the smallest dose necessary to control the signs and symptoms. Patient’s with acute or chronic urticaria who do not respond to antihistamines may be treated with short courses of corticosteroids.
Antihistamines (H1 receptor antagonists, H2 receptor antagonists)
H1 receptor antagonists such as Zyrtec are the most commonly used antihistamines.
Hydroxyzine and diphenhydramine are very effective but cause varying degrees of sedation. The dosage of hydroxyzine can be varied over a wide range. A balance must be reached between the side effects of sedation and the efficacy of the drug. Adults with acute urticaria can take 25 mg every 4 hours as initial therapy. Those patients who are rapidly controlled to him over the dosage. The dosage can be increased to as high as 100 mg every 4-6 hours if necessary. A dose this high is rarely required. Hydroxyzine is available as a liquid at 10 mg per 5 cc. Hydroxyzine is available in generic form in 10 mg, 25 mg, 50 mg and 100 mg tablets.
Nonsedating antihistamines are less effective and do not have the flexibility of dosing that hydroxyzine allows. Cetirizine (Zyrtec) 5 mg or 10 mg is taken once daily. Some patients experience mild sedation with cetirizine. Clarinex (desloratadine) 5 mg once a day is effective in many instances and is rarely sedating.
H2 receptor antagonists such as ranitidine and cimetidine are sometimes prescribed in combination with H1 receptor antagonists. Most clinicians feel that there is little advantage in using this combination and that monotherapy with H1 receptor antagonists is just as effective.
Patient’s not responding or only partially responding to antihistamines can be treated with short courses of corticosteroids. Prednisone 30-60 mg taken as a single dose in the morning or divided for twice a day dosing can be used for several days to gain control. Prednisone is tapered rapidly and withdrawn once the therapeutic effect is obtained.
A number of other treatments are available for difficult to control cases of acute and chronic urticaria. Extensive acute urticaria is sometimes treated in the emergency room with epinephrine. Chronic urticaria unresponsive to antihistamines can be treated with doxepin, leukotriene receptor antagonists, and immunosuppressants such as tacrolimus and cyclosporine.