Question

What are antihistamines? Give two examples.

Answer 1

Hint: Antihistamines are the type of drugs which are used to treat allergies. The allergies are categorized into sneezing, hives or urticaria, nasal congestion and other animal and food allergies. These are called antihistamines because they prevent the effect of histamine which is produced by our body.

Complete step by step answer:
Antihistamines are the drugs that prevent the release of histamine which causes itching, watery eyes, sneezing and runny nose. Steroids are also used to treat allergies but first antihistamines are preferred to block the release of histamine. Antihistamines are available in capsules, tablets liquids, nasal sprays, and eye drops.
Histamine is an organic nitrogenous compound which is released by the mast cells when the body encounters an allergen. It causes inflammation and itching effects. Mast cells are present in the skin and mucous membrane. The unwanted release of histamine is a result of autoimmune disorder in which the body attacks normal healthy tissues causing allergic symptoms which mainly include redness and inflammation of skin along with itching. Hives or urticaria is an autoimmune disease in which the healthy tissues get attacked and the histamine release causes allergic symptoms. Antihistamines are used to get relief from such types of allergies. These are the antihistamines commonly taken- Levocetirizine, Fexofenadine (Allegra) and Loratadine.
The structure of histamine is:

Note:
Whenever the body comes in contact with an allergen it can be pollen grains, dust, peanuts, anything from which a person is allergic, the body starts producing a chemical known as histamine which causes rashes, sneezing and running nose. To control the release of histamine, antihistamines are taken. There also exist natural antihistamines like Vitamin C and Quercetin which helps in relieving from minor allergies.