Histamine, antihistamines and atopic eczema

Abstract

Histamine is known to be a classical inducer of pruritus. In atopic eczema, itch is a prominent feature (regarded by some even as a 'primary lesion'!). One of the most potent chemical mediators of itch is histamine. Histamine, together with other mediators may play a role in the pathophysiology of atopic eczema: the increased release of histamine from basophil leucocytes of atopic patients has been described, as well as elevated histamine levels in plasma and skin during acute exacerbations of eczematous lesions. Therefore, application of H1 antagonists seems to be a rational regime in the symptomatic treatment of atopic eczema. Nevertheless, some controversy exists regarding the clinical efficacy of orally applied H1 antagonists in this disease, especially with regard to the newer non-sedating compounds such as terfenadine, astemizole, loratadine and cetirizine. Review of the literature shows that there are studies demonstrating a clear-cut antipruritic effect of non-sedating H1 antagonists. Thus the sedative action does not seem necessarily to be connected with therapeutic efficacy in treating itch in atopic eczema. Newer studies show that cetirizine exerts an additional inhibitory effect on eosinophils. This may broaden the therapeutic spectrum of this H1 antagonist in diseases with eosinophil involvement.

Antihistamines in the Treatment of Atopic Dermatitis

“…4 Antihistamine therapy can include the use of conventional H 1 antagonists, newer nonsedating H 1 antagonists, and the combined application of H 1 /H 2 antagonists. [14][15][16] Recently, third-generation antihistamines have also been indicated for use (Table I). The firstgeneration or traditional antihistamines act on both the central and peripheral H 1 receptors and are associated with somnolence and anticholinergic effects.…”

Scalp Stratum Corneum Histamine Levels: Novel Sampling Method Reveals Association with Itch Resolution in Dandruff/Seborrhoeic Dermatitis Treatment

“…The perception of itch represents the end of a complex physiological pathway initiated at the skin surface by a number of stimuli that can cause the release of histamine fi-om mast cells in the dermis (6). Using invasive sampling techniques, higher tissue histamine levels have been previously found in eczema (17), psoriasis (18,19) and dry skin (9), and, importantly, itch frequently accompanies these conditions. While histamine levels in D/SD have not been investigated in the past, topical application of exogenous histamine to subjects with dandruff increases the severity of itch (13), suggesting an association between itch perception and histamine levels, whether exogenously supplied or endogenously stimulated.…”

Association Between Eczema and Increased Fracture and Bone or Joint Injury in Adults

“…mine use, 12 and psychological comorbidity. 3 Sleep impairment is a particularly well-known risk factor for increased injury risk [13][14][15] and affects a high percentage of patients with eczema.…”