Abstract
There are two known types of histamine receptors, H1 and H2. Recent evidence revealed that human skin blood vessels possess both types of receptors. Thirteen patients with chronic urticaria were prescribed H1 (hydroxyzine) and H2 (cimetidine) antihistamines alone and in combination, in a cross-over trial. Combined H1 and H2 antihistamine therapy resulted in improvement in duration and distribution of wheal and itching, but there was no significant difference in wheal size. Twelve of thirteen patients reported improvement in subjective symptoms while on the combination therapy. Thus, H1 and H2 combined antihistamine therapy seems to be effective in controlling chronic urticaria.
