title: Efficacy and safety of H1-antihistamines: an update.
abstract: H1-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-α-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 current literature to evaluate antihistamines including their mechanism, indications and side-effects.
authors.affiliation: Department of Immunology and Allergic Diseases, Faculty of Medicine, Kirikkale University, Kirikkale, Turkey. afusunk@yahoo.com
authors.forename: Fusun
authors.initials: F
authors.lastname: Kalpaklioglu
authors.forename: Ayse
authors.initials: A
authors.lastname: Baccioglu
mesh_terms: D000369:Aged, 80 and over; D018926:Anti-Allergic Agents / Q000627:therapeutic use*; D001942:Breast Feeding; D002493:Central Nervous System Diseases / Q000188:drug therapy; D002675:Child, Preschool; D005260:Female; D006634:Histamine H1 Antagonists / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D006967:Hypersensitivity / Q000188:drug therapy*; D007774:Lactation; D056687:Off-Label Use; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy; D013678:Technology, Pharmaceutical; D015837:Vestibular Diseases / Q000188:drug therapy
chemical_list: D018926:Anti-Allergic Agents; D006634:Histamine H1 Antagonists