Antihistamines work by blocking the effects of a chemical called histamine that is responsible for many allergic symptoms.
These antihistamines will not be discussed further.) Antihistamines also may be used to treat motion sickness, insomnia (difficulty sleeping), and anxiety.
Antihistamines also can be used on an as needed basis for those who experience occasional symptoms or symptoms triggered by exposure to certain irritants such as animal hair, plants, medications, and food products.
Some antihistamines also may be used occasionally to help with sleep.
Antihistamines work by altering the way cells are affected by a substance called histamine.
A drug may be classified by the chemical type of the active ingredient or by the way it is used to treat a particular condition.Each drug can be classified into one or more drug classes.