Kalpaklioglu F.Baccioglu A.2020-06-252020-06-25201218715230https://doi.org/10.2174/1871523011202030230https://hdl.handle.net/20.500.12587/2216H1-antihistamines are inverse agonists that combine with and stabilize inactive conformation of H1-receptors. Thus they interfere with actions of histamine at H1-receptors. They are widely used for treatment of allergic rhinitis, allergic conjunctivitis, urticaria, coughs, colds and insomnia. H1-antihistamines are classified as older 'first generation' and newer 'second generation'. First generation H1-antihistamines have poor receptor H1-receptor selectivity, and cross blood-brain-barrier. They have a lot of adverse events such as anti-muscarinic, anti-?-adrenergic, anti-serotonin, and sedative effects. In contrast, second generation H1-antihistamines were highly selective for the histamine H1-receptor, do not cross the blood brain barrier, and have minimal adverse events. The risks of first-generation H1-antihistamines have been clearly underestimated, particularly when purchased as nonprescribed over the counter medications by public. This review summarizes curent literature to evaluate antihistamines including their mechanism, indications and side-effects. © 2012 Bentham Science Publishers.eninfo:eu-repo/semantics/closedAccessAdverse eventsAllergic rhinitisAntihistamine(s)Atopic dermatitisCardiotoxicityHistaminePharmacologyReceptorSleepUrticariaReview Article11323023710.2174/18715230112020302302-s2.0-8487652869523173575Q3