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Allergy
By
Talsk Research's Physician Group
Overview
An
allergy is an abnormal reaction of the body’s immune system
that occurs in response to generally harmless substances such as
pollen, dust, certain foods, mold, animal dander, which are referred
to as triggering factors or “allergens”. In a person
with allergies, the oversensitive immune response fights off the
allergens and in the process releases chemicals such as histamine
which can cause symptoms that can vary anywhere from itchy and runny
nose, itchy and watery eyes and itchy palate, cough, skin rash and
hives to airway obstruction or anaphylaxis needing emergent
treatment.
Some
of the common types of conditions caused by allergies include hay
fever, asthma, eczema, contact dermatitis (skin reactions),
conjunctivitis (pink eye), sinusitis and occasionally a life
threatening reaction called anaphylaxis. The timing of the symptoms
is usually related to the presence of triggering factors in a
particular season or location. Symptoms appear seasonally if
allergies are due to pollen or weeds and are nocturnal if the
triggering factors are dust mites.
Causes
In
response to the presence of the allergens, the body’s defense
mechanism produces special type of protein (antibody -
immunoglobulin) to attack the invading material. This in turn leads
to other blood cells to release more chemicals like histamine (a
substance that dilates blood vessels and makes the vessel walls
abnormally permeable), which together cause the symptoms of an
allergic reaction.
Some
of the common allergens include:
Dust
mites
Grass
and tree pollen
Pet
hair or skin flakes
Fungal
or mold spores
Food
: milk, eggs, wheat, soya, seafood, fruit and nuts, shell fish
Wasp
and bee stings
Certain
medication such as penicillin and aspirin
Latex
Household
chemicals
Tobacco
smoke
Symptoms
Symptoms
generally depend on the type of the allergen, the part of the body in
contact with the allergen, and the immune response a particular
person might have to the allergen. Common symptoms include:
Red
and generally itchy bumps on skin (hives), especially over the neck
and face
Itching
of the mouth, lips, tongue, throat, eyes, skin
Nasal
congestion and runny nose
Tickle
in the throat
Skin
rashes or eczema (scaly skin which may peel and blister)
Watery,
Itchy and red eyes (allergic conjunctivitis)
Flushing
or redness of the face
Difficulty
in breathing, wheezing or asthma
Difficulty
in swallowing
Abdominal
pain or cramps with or without diarrhea
Nausea
and vomiting
Anaphylaxis
or a severe and explosive allergic reaction involving the whole body
and can include life threatening symptoms such as
Swelling
of the throat and airways making breathing very difficult
Swelling
of the face, eyes, tongue, and lips resulting in hoarseness
Fear
or feeling of apprehension or anxiety
Palpitations
Dizziness
or light-headedness
Loss
of consciousness
Diagnosis
A
detailed history of the patient’s symptoms and their timing,
environmental exposures, personal and family history and a physical
examination will help the doctor a great deal in diagnosing
allergies. Some of the following tests may be performed to identify
the triggering factors:
Skin
Tests
Prick
test: This involves placing a small amount of allergens on the skin
and pricking the area, so that the allergen goes under the skin
surface. Results are seen within minutes.
Intradermal
test: This involves injecting a small amount of allergen into the
skin to find out allergic reactions against something specific, like
bee venom or penicillin. Results are seen within minutes.
Patch
test: Possible allergens are taped to the skin for 48 hours and the
area is examined for redness and swelling in 24 hrs and 48 hrs.
Elimination-type
Test
This
test is usually used to check for food allergies.
Blood
Tests
Provocation
This
(challenge) testing involves exposing a person to a suspected
allergen.
The
allergic reactions can be very severe and a doctor should oversee
this type of testing.
Treatment
and Prevention
Avoiding
allergens should be the topmost priority in treating allergies but as
that is not always possible, an attempt to reduce the exposure to the
allergens should be made. Following are some precautions one might
want to consider depending on the triggering factors:
Use
a vacuum cleaner fitted with a HEPA (high efficiency particulate
air) filter and the house should be free of mold
Limit
contact with pets as much as possible
Bathe
and Groom pets at least once every week
Carefully
check the label of a food product
Check
weather reports for the pollen count and stay indoors when the
counts are high
Breastfeeding
babies as long as possible might help proper development of their
immune systems.
Always
carry a self injection adrenaline kit if there is a history of
anaphylaxis
Although
medications cannot cure allergies, they can ease the symptoms such as
a runny nose, itchy mouth, sneezing and asthma associated with
allergies. Though most treatments are available over the counter, it
is always safe to ask your doctor for advice before starting any new
medication.
Antihistamines:
First generation antihistamines like Chlorpheniramine and Benadryl
(Diphenhydramine) can cause drowsiness but second generation
antihistamines like Claritin, Zyrtec, Allegra are less inclined to
cause drowsiness
Antihistamine
nasal sprays such as Astelin is a nasal spray that can help relieve
nasal symptoms without affecting other parts of the body
Oral
decongestants: Pseudoephedrine or Sudafed is a very common oral
medication used to relieve sinus and nose congestion.
Nasal
Decongestants: Nasal sprays such as Afrin relieve congestion but
only provide temporary relief and should be used sparingly
Different
combinations of antihistamines and decongestants both orally and as
nasal sprays are available and work very effectively. Claritin-D,
Allegra-D, Tylenol Allergy and Sinus are some examples.
Corticosteroid
nasal sprays such as Flonase and Nasonex reduce inflammation of the
nasal mucosal lining and if taken regularly can significantly reduce
the need for antihistamines and decongestants
Antihistamine
eye drops like Patanol and decongestant eye drops such as naphcon
and Vasocon reduce itching and tearing of eyes but can have severe
side effects if overused.
Inhaled
steroids and bronchodilators for symptoms related to allergic asthma
Leukotriene
inhibitors such as Singulair specifically block the mediator
chemicals called leukotrienes produced by the body in response to
the allergens which are responsible for most of the allergy
symptoms.
Allergy
shots: the doctor injects small doses of suspected allergens under
the skin.
Oral
Corticosteroids: They reduce inflammation and affect the immune
system but can have several undesirable side effects such as
increased blood pressure, weight gain, bone loss etc and so are
reserved to cases not responding to other treatments.
Treating
anaphylaxis: Severe allergic reactions (anaphylaxis) require
treatment with a medicine called epinephrine, which can be life
saving when given immediately.
Credits:
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References
All
information provided above is for basic awareness and education
purposes only and should not be used for diagnosis or treatment of
any medical condition under any circumstance. Please consult a
licensed medical professional for these purposes. In case of medical
emergency please call 911.
Copyright
2011 Talsk Research Inc. All rights reserved.
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