$Unique_ID{BRK02421}
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$Title{What Is an Antihistamine and How Does It Work?}
$Subject{antihistamines runny nose itching swelling antihistamine histamines
allergic reactions antigen allergy mast cells rhinorrhea lungs airways
bronchioles wheezing breathing skin redness nasal congestion medicine
medicines medication medications lung bronchi running allergies}
$Volume{R-5,R-20}
$Log{
The Process of an Allergic Reaction*0001201.scf
Histamine Release Causes Allergy Symptoms*0001202.scf}

Copyright (c) 1992,1993   Tribune Media Services, Inc.


What Is an Antihistamine and How Does It Work?


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QUESTION:  I am confused by the use of antihistamines.  It seems that they are
used for many different symptoms, from runny noses to itching and swelling.
Just what is an antihistamine, and could you describe just how they work in
words I might understand?  I thank you for your response.

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ANSWER:  To understand the working of antihistamines, you need to know just a
bit about the role played by histamines in allergic reactions.  The first
knowledge of some of these actions were first described by Sir Henry Dale, who
won a Nobel prize for his contributions to medical science in 1936.
     When a antigen (or allergy provoking substance) comes in contact with the
surface of certain cells in the body (called "mast" cells) a substance called
histamine is released.  Then this histamine attaches to receptors on
surrounding cells, which provoke the common allergic reactions we have come to
recognize
     The responses are different depending upon the organ system involved.  In
the nose, they are sneezing, itching and rhinorrhea (runny nose).  When
histamine is released in the lungs, the airways (bronchioles) constrict
causing wheezing and breathing difficulty.  Reactions in the skin include
redness, swelling and itching.
     Antihistamines are chemicals that attach to the receptors that are
normally reserved for histamine, and so the reactions are prevented or
blocked.  Itching is relieved and the nasal congestion is reduced.  But there
is a problem in this very complex system.  When the mast cells are stimulated
by the antigens, other types of chemicals which affect blood vessels and
smooth muscle and play a role in allergic reactions, are also released.
Unfortunately antihistamines have no effect on these other factors, and so
treating the symptoms only with antihistamines may not offer complete relief
of the symptoms provoked by the allergy.

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The material contained here is "FOR INFORMATION ONLY" and should not replace
the counsel and advice of your personal physician.  Promptly consulting your
doctor is the best path to a quick and successful resolution of any medical
problem.