In fact, most over-the-counter sleep aids contain antihistamines.
These products are intended to be used for only two to three nights at a time, however, such as when stress, travel or other disruptions keep you awake.
Histamine carries its message to a large number of cells by attaching to a special receptor on the cells' surfaces.Antihistamines are inhibitors of histamine receptors. H1-antihistamines, inhibit competitively H1 receptors and the corresponding effects i. They do not inhibit antigen/antibodies reactions, nor histamine release, they inhibit H1 effects. H1-antihistamines have been used for more than fifty years in treating various allergic manifestations. H1-antihistamines which penetrate into brain elicit, by inhibiting stimulant effect of histamine, drowsiness.In addition, each compound can have or not have parallel properties, antimuscarinic effects for example.This distinction between generations must be taken with caution because a product considered as non sedative or not antimuscarinic can, in certain circumstances, large doses or particular susceptibility of the patient ,have these effects.Skin sensations local itching or burning sensation, flushing and a disagreeable heat.