When you inhale an allergen, mast cells located in the nose and sinus membranes release histamine.
Histamine then attaches to receptors on nearby blood vessels, causing them to enlarge (dilate).
Antihistamines help relieve symptoms by blocking the action of histamine.
Histamine is a naturally occurring substance that is released by the immune system after being exposed to an allergen.
Histamine also binds to other receptors located in nasal tissues, causing redness, swelling, itching, and changes in the secretions.
By blocking histamine receptors, antihistamines prevent symptoms.
More than 40 million people suffer from nasal allergy symptoms in the United States.
Over-the-counter (OTC) medications for allergy relief fill the shelves of retail pharmacies and there always seem to be new ones coming to the market.
Over the last ten years several allergy medications have disappeared as new ones have arrived.
Choosing the right medication often depends on matching your symptoms with what the colorful medicine box states the drug inside is capable of relieving. All About Antihistamines Antihistamines are the most common drugs taken to treat nasal allergy symptoms.
It can be very disappointing when runny nose, sneezing and nasal congestion remain unaffected by the “miracle drug.” In desperation, you may decide to double the dose or add another OTC allergy medication. There are two major classifications of antihistamines: Since the beginning of this decade, two second generation antihistamines have become available for OTC purchase: loratadine (brand of Claritin, Alavert, Wal-itin and others) and cetirizine (brand of Zyrtec, Walzyr and more coming).
Antihistamines Antihistamines are one of the most important medications for treating allergies.
Antihistamines help relieve, sneezing, itching, runny nose and may help reduce congestion.