" April 25, 2003 -- Timely research for the start of hay fever season: Despite their higher cost, the newer, so-called "second generation" of more expensive "nonsedating" prescription antihistamines may be no more effective at preventing fatigue and memory lapses than older over-the-counter formulas such as Benadryl.So concludes a new study published in the current issue of Journal of Allergy and Clinical Immunology in which researchers compared 18 previous trials investigating antihistamine-caused sedation levels in 1,500 people between ages 8 and 81.Their main benefit is they primarily affect peripheral histamine receptors and therefore are less sedating.However, high doses can still induce the central nervous system drowsiness.It is the release of histamine that causes the body to protect itself from the pathogens in ways that we recognize as an allergic reaction.Histamine is responsible for the immune response to the stimuli that we are familiar in symptoms as itching, sneezing, hives, runny nose and watery eyes. Traditional antihistamines act by minimizing swelling and controlling the dilation of small blood vessels that translate to those common allergy symptoms.Non-sedating antihistamines are helping to improve the lives of countless people who suffer from the symptoms of serious allergic reactions.
Seasonal allergic rhinitis: 60 mg orally twice daily or 180 mg once daily.Antihistamines that target the histamine H receptors in the upper gastrointestinal tract, primarily in the stomach.Histamine receptors exhibit constitutive activity, so antihistamines can function as either a neutral receptor antagonist or an inverse agonist at histamine receptor.Bender, Ph D, of National Jewish Medical and Research Center in Denver."The first-generation antihistamines are more sedating, but the distinction isn't as black-and-white as the marketing of the newer products may lead you to believe.PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE.BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.Please see package insert for additional information and possible updates.The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical judgment. nor any other party involved in the preparation of this program shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.This content has not been reviewed within the past year and may not represent Web MD's most up-to-date information.To find the most current information, please enter your topic of interest into our search box.