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In the strictest sense, anti-histamines are H1 histamine receptor antagonists. This means they block histamine from reacting with the H1-receptors, countering the effects of Histadelia that would normally result from H1 receptor stimulation. Thus, anti-histamines are often prescribed to relieve the symptoms of hayfever, rashes, and allergies. Examples of these type of anti-histamines are:

NameTradenames /



Benadryl, Dimederol, Nytol

Used to treat colds and flu, and as a sleeping pill.

Benadryl - click for 3D structure Benadryl space fill structure - click for 3D structure



Claritin, Claritin-D, Claritine, Clarityn, Clarityne, Fristamin, Lomilan, Symphoral, Roletra, Rinolan, AllergyX, Alavert or Clarinase

Used to treat allergies.

Loratadine - click for 3D structure Loratidine - spacefill - click for 3D structure



Bonine, Antivert

Used to prevent motion sickness, vertigo and nausea.

Meclizine - click for 3D structure Meclizine - spacefill - click for 3D structure



Seroquel, Ketipinor

Used to treat psychosis, schizophrenia, and acute manic episodes associated with bipolar disorder.

Quetiapine - click for 3D structure Quetiapine - spacefill - click for 3D structure

It is now possible to get other histamine receptor antagonists. For example, a number of H2 blockers are available which are used to reduce stomach acid, or in the teatment of stomach ulcers. These include: Cimetidine (Tagamet), Famotidine (Pepcidine, Pepcid), and Ranitidine (Zinetac, Zantac). H3 blockers are used to make people more awake, by allowing more histamine to be produced, therefore triggering more H1 receptors.