Pharmacology of Antihistaminics (Autacoids Part 3) | Dr. Shikha Parmar 

Pharmacology of Antihistaminics (Autacoids Part 3) by Dr. Shikha Parmar
Histamine antagonists are the drugs that bind to but do not activate histamine receptors, thereby blocking the actions of histamine or histamine agonists. ... Antihistamines that target the histamine H1-receptor are used to treat allergic reactions in the nose (e.g., itching, runny nose, and sneezing).
Antihistaminic drugs or histamine blockers are the drugs which block the action of histamine or its release. Histamine is responsible for local action like- itching and other allergic response. Antihistaminic drugs are useful in following categories-
1- Anti Allergic Rhinitis by Antihistaminic Drugs
2- Anti Conjunctivitis by Antihistaminic Drugs
3- Anti Hay Fever- by Antihistaminic Drugs
4- Anti Pollinosis by Antihistaminic Drugs
5- Dermographism by Antihistaminic Drugs
6- All other kinds of an allergic reaction
Description Source: Wikipedia