| Antihistimines
are drugs that block the action of histamine.
There are special histamine-receptor cells
spread in tissues around your body. When the chemical histamine
is released into the blood, it attaches to these receptor
cells.
This causes the blood vessels to widen, increasing
blood flow to areas where there are receptors, such as the
nose, which makes the area swell up and produce mucous, itching
and other symptoms.
There are two main types of histamine receptors.
H1 receptors are mainly found in the small blood vessels in
the skin, nose and eyes. Antihistamines that block H1 receptors
are used to treat allergies, such as hay fever, that cause
symptoms like itching, sneezing, and watering eyes.
H2 receptors are found mainly in the stomach
lining. When histamine attaches to a H2 receptor, it releases
acid into the stomach. Antihistamines that work on H2 receptors
are therefore used to treat stomach ulcers. They stop acid
being produced and give the stomach’s protective, mucous
lining time to heal itself.
Antihistamines work by stopping histamine getting to the histamine
receptor cells. This stops the blood vessels from widening,
so prevents the allergy symptoms. The antihistamine drug also
gets into your bloodstream and travels through the blood to
your brain.
Depending on the type of drug, it can act
on the brain to produce other effects such as drowsiness,
and to block the reflexes that make you vomit or cough.
What
are Antihistamine drugs? |
How
does it work? | What
is it used for? | Who
can use it?|
Side
effects|
Managing
Allergies During Pregnancy|
Asthma
in Pregnancy|
How
To Survive Spring Allergies|
Allegra
A Common Anti Allergy Drug|
Practical
Measures to Prevent and Treat Allergy|
Give
Your Allergies A Sniffle-Free Spring |
