http://www.rxboomer.com/articles/Antihistamines_Summary.html Antihistamines are drugs used to reduce the effect of a natural chemical released during allergic reactions called histamine. For this reason, it is commonly used to treat allergies, allergic reactions, fever and cold symptoms. Antihistamines block the action of histamine at receptors in the nose, skin, airways and blood vessels. Although histamine is produced naturally to defend the body, too much of it can cause allergic reactions. These drugs can also be used to treat other diseases such as dizziness, motion sickness, tickly coughs and poor sleep. Need more information? Read the articles we have at your disposal. en-us