Role of histamine and antihistamines in the nose.

The effect of an H1 antihistamine (chlorpheniramine) and an H2 antihistamine (ranitidine) nasal spray on histamine-provoked symptoms was studied in normal volunteers. Firstly it was shown that the H1 antihistamine has a marked inhibiting effect on tickling, sneezing and discharge, and secondly, that both H1 and H2 antihistamines have a weak effect on blockage. Finally, it was found that the H1 antihistamine, in the concentration used, has no demonstrable anti-cholinergic or local anaesthetic effect. It is concluded that antihistamines act locally in the nose, H1 antihistamines inhibit tickling, sneezing and hypersecretion via nervous H1 receptors, while blood vessels possess both H1 and H2 receptors.