title: AOA's current trends in pharmacology and therapeutics histamine and antihistamine agents.
abstract: BACKGROUND
  Drugs that selectively block the H-1 subtype of histamine receptors are known as classical antihistamines.
  
  
  METHODS
  These agents are used for the symptomatic relief of allergies and colds and because they act in a manner similar to atropine, and are often used for their anticholinergic effects. They are readily available as prescription and over-the-counter medications and it is likely that the practicing optometrist will encounter these drugs in their patient population.
  
  
  RESULTS
  Antihistamines produces several common ocular side effects that include blurred vision, diplopia, mydriasis, and decreased lacrimation.
  
  
  CONCLUSIONS
  This article reviews the physiology of histamine as it relates to the pharmacology of antihistamines, the mechanism of action, and adverse effects associated with the classical antihistamines.
authors.affiliation: Southern College of Optometry, Memphis, TN 38104.
authors.forename: K
authors.initials: K
authors.lastname: Blaho
mesh_terms: D000075202:Contraindications; D004347:Drug Interactions; D006632:Histamine / Q000494:pharmacology* / Q000627:therapeutic use; D006634:Histamine H1 Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans
chemical_list: D006634:Histamine H1 Antagonists; D006632:Histamine