Antihistamines are one of the most commonly used OTC and
prescribed medications. They are beneficial for nasal and
eye allergies, eczema, and hives but tend not to be
effective in asthma.
Antihistamine is a combination of two words. "Anti-"
means against, and "histamine" is a naturally occurring
chemical that is released by the mast cells.
How do antihistamines work?
Human cells have three different types of histamine
receptors (H1, H2, and H3). Histamine works by attaching
itself to these receptors on the surface of cells and
thereby causing its effects. It is mainly through the H1
receptors that histamine causes symptoms of allergy.
Antihistamines act by attaching to these same H1 receptor
sites, thereby preventing histamine from binding to them.
This action prevents the histamine from causing allergic
symptoms.
Histamines can cause
swelling, sneezing, itching (nose, throat, roof of mouth),
and a runny nose through the nostrils or down the back of
the throat (post-nasal drip). Antihistamines are effective
in treating the sneezing, running, and itching. They
usually begin working between 30 to 60 minutes after being
taken. However, histamine is only one of the many
chemicals involved in the allergic reaction, which explains
why relief from antihistamines is usually only partial.
Allergy Fact
Bovet and Straub at the Pasteur Institute discovered the
first antihistamine in 1937. It was too weak, however, and
caused many side effects. In 1942, phenobenzamin (Antegan)
was the first antihistamine used to treat allergies.
Within a few years, diphenhydramine (Benadryl) and
tripelennamine (PBZ) were formulated.
Allergic rhinitis symptoms include an itchy, runny nose, sneezing, itchy ears, eyes, and throat. Seasonal allergic rhinitis (also called hay fever) is usually caused by pollen in the air. Perennial allergic rhinitis is a type of chronic rhinitis and is a year–round problem, often caused by indoor allergens, such as dust, animal dander, and pollens that may exist at the time. Treatment of chronic rhinitis and post nasal drip are dependant upon the type of rhinitis condition.
An allergy refers to a misguided reaction by our immune system in response to bodily contact with certain foreign substances. When these allergens come in contact with the body, it causes the immune system to develop an allergic reaction in people who are allergic to it. It is estimated that 50 million North Americans are affected by allergic conditions. The parts of the body that are prone to react to allergies include the eyes, nose, lungs, skin, and stomach. Common allergic disorders include hay fever, asthma, allergic eyes, allergic eczema, hives, and allergic shock.
Hay fever (allergic rhinitis) is an irritation of the nose caused by pollen and is associated with the following allergic symptoms: nasal congestion, runny nose, sneezing, eye and nose itching, and tearing eyes. Avoidance of known allergens is the recommended treatment, but if this is not possible, antihistamines, decongestants, and nasal sprays may help alleviate symptoms.
Common sources of indoor allergens include dust mites, cockroaches, molds, pets, and plants. Managing allergies caused by indoor allergens means reducing your exposure to them.
Allergy RSS
Healthy Living Tips
This site complies with the