- Causes & Risk Factors
- Signs & Symptoms
- Stages: (if applicable)
- Medical Tests & Diagnosis Methods/Tools
- Treatment Options
- Prevention Methods
Allergies and other type of immune hypersensitivities are important undesirable side effect
of our immune system. These problems occur in people who have a specific allergic tendency.
Anyone suffering from allergy can take comfort that there are over 50 million fellow American
sufferers of this problem. Roughly one in 6 American is afflicted with allergic problem.
Fortunately, in very few people allergic condition can become life threatening. In most allergy
sufferers problems due to allergy appear to be trivial such as runny nose, sneezing, itchy eyes, sinus
problem, rash and skin complaints but these otherwise minor problems can make the allergy
sufferers lives quite miserable.
Our immune system, essential for defending our bodies against foreign organisms, produces
antibodies and activated white cells to attack invaders like viruses and bacteria. Occasionally, the
immune response results in an inappropriate or exaggerated reaction called hypersensitivity.
Hypersensitivity is classified into four types; Types I, II, III and IV. Types I to Type III
hypersensitivities are antibody-mediated while Type IV is a cell mediated hypersensitivity. Type II
& III are Immunoglobulin G (IgG) mediated while Type I sensitivity is Immunoglobulin E
mediated. The term „Allergy‟ is confined to IgE mediated reactions or Type I hypersensitivity
[Levinson, 2004] .
Immunoglobulin E (IgE) is our body‟s host defense system against certain parasites such as
worms. In developed countries, where parasitic infection is uncommon, most people have no or
very low level of IgE. An allergic reaction or allergy occurs when our body‟s immune system
mistakenly considers a harmless substance, called „allergen‟ as dangerous and starts producing IgE
to trigger an allergic reaction [Levinson, 2004].
Types of Allergies
This type of allergy causes swelling of nasal mucosa with respiratory discomforts like
sneezing and runny nose by inhaling allergens such as pollen, molds, dust, dander and other
The allergic reaction affects the eyes, redness and itching are the signs of this allergy.
Wheezing and shortness of breath caused by narrowing of bronchial cavities. Asthma is a
serious type of bronchoconstriction. This type of allergy is also caused dust, pollen, mites, and other
The allergens affect ear passages causing pain and impairing hearing.
Itchy rashes, blisters, hives, and contact dermatitis caused by touching certain substances
such a poison ivy or food items are manifestation of this type of allergy. In allergies where swelling
occurs as a result of hives, swelling can cause breathing and swallowing difficulties.
Certain kind of foods, such as fish egg, nuts and milk can cause intestinal upsets due to
Time Delayed Allergies:
An allergic response appearing hours or days after application or absorption of an allergen;
including contact dermatitis and bacterial allergy [Allergies, 2006]
This is the most severe systemic allergic reaction causing bronchoconstriction, swelling of
body tissues, vomiting, cramps, skin reactions and drop in blood pressure, coma and even death
[Guyton & Hall, 2006].
Allergy can also be classified on the basis of its effect and allergen as:
Causes & Risk Factors
Problems with normal immune responses are believed to be the result of both genetic and
environmental factors. Children of allergic parents are more likely to have similar allergies though
the allergens may differ. [Allergies, 2006] Genetic research is leading scientists to believe that skin
and tissue specific genes may be responsible for causing allergy symptoms [NIH, 2000]. Stress and
anxiety are acknowledged a common cause of allergic reaction. [Lenzoff, 1997] subjected patients
suspected of multiple chemical sensitivities concluded that in some sufferers allergy symptoms
might be triggered by their perception of an environmental insult.
Increasing use of chemicals has resulted in introduction of new toxins into the atmosphere.
The increase in number of allergy cases during the last decades is often attributed to atmospheric
pollution [Bornehag et al, 2004]. Better identification of problem as allergy and not other minor
condition such as cold is perhaps also responsible for increased numbers.
Allergy or Cold
A number of symptoms of common cold are also the symptoms of allergy. It is not unusual
to mistake one for the other. The major difference between the cold and flu are [Allergy, 2006b]:
- Both cold and allergy show the common symptoms of allergy but the cold is also
accompanied by fever and pain.
- Allergy begins immediately after exposure to the allergen while cold takes a day or
more to develop to full strength.
- Cold is a self terminating diseases and the symptoms disappear in 3 to 7 days while
allergies continue till the person remains exposed to the allergen
The body‟s immune system has the capability to attack a foreign organism. If it identifies a
substance such as pollen as foreign, even mistakenly, the defense mechanism comes into action and
IgE is produced to fight off that particular substance. Thus, there will be separate IgE for pollen and
for dust allergies. There are many allergens as any person could be allergic to a common substance,
which is not an allergen to others, but the common allergens include pollen and fungus from weeds,
grasses. Trees and outdoor mold, dog and cat dander, dust particles, noxious vapors and smog,
foods such as fish, eggs, nuts and insect bites.
Signs & Symptoms
In addition to the usual sneezing, runny nose, rashes allergy and red or itchy eyes symptoms
include atopic dermatitis, contact dermatitis, headache, earache, hives, coughing, sinusitis, and other
Medical Tests & Diagnosis Methods/Tools
The diagnostic tests for Allergy include:
Skin Prick Test (SPT)
Total IgE Test
Range of Specific IgE Test
Specific IgE Pediatric Food Mix fx5
Skin Prick Test:
Skin prick test is a common and simple method of diagnosing allergy. In this test small
amount of suspected allergens are injected either intra-dermally or into the scratching made in the
patient‟s skin. Patient allergic to any of the allergen shows a visible inflammation after half an hour.
Skin Prick Test (SPT) only responds to allergens used in the test. In cases where patient is
allergic to any other allergen, this test will not show. Some patients with delayed type
hypersensitivity may be adversely affected by the test.
Total IgE Test:
Patient serum IgE test is another method used for determining Type I hypersensitivity. The
test provides useful indication for allergy. This test however is not considered conclusive. The test
measures total IgE value and is said to be only to report existence of allergy 60% of the time
[Labspec, 2006]. The extent of symptoms and type of allergy has an effect on the result. Severe skin
allergy shows a higher IgE value than rhinitis or conjunctivitis. [Labspec, 2006] also point out that
Standard IgE values appear to vary with ethnicity of the patient.
Range of Specific IgE Test:
Some diagnostic suppliers are manufacturing specific IgE test for allergens. Specific tests for over
400 allergens are available. Some of these specific tests have been approved for routine tests, other
are awaiting approval. [Labspec, 2006]
Instead of testing total IgE or specific test for a single allergen, this test tests serum for a
wide range of inhalant allergens. The test is said to be 95% reliable and can be used to exclude
allergens included in Phadiatop assay.
Specific IgE Pediatric Food Mix fx5
His test is similar to Phadiatop Assay, but instead of inhalant allergens, ingestant allergens
are tested. This test is still in approval stages for general laboratory use.
Many people with mild allergies avoid seeking medical help, but it is important to know that
allergies if left untreated can develop into serious health problems like infections in sinuses, throat
and ears, chronic respiratory problems, skin problems such as eczema. The treatment Options for
Avoid allergen environment and/or food
Over the counter medication (histamines)
Prescription drugs & nasal drops,
Once a person knows the substance that causes allergy, the best treatment is to avoid that
substance. However avoiding allergen is not always possible as it is not possible to breathe. Food
allergens can be easily avoided [When Should I Get Medical Treatment for Allergy, 2006] .
In a very large number of cases of mild allergy over the counter medication is all one needs
to relieve the symptoms. It is important to consult a doctor for over the counter medicine too, as
some of these medicines if used excessively can cause serious side effects. Most of the histamines
Antihistamines and decongestants relieve the symptoms of most allergy sufferers. Again, a
physician‟s advice should be sought. Many new antihistamines relieve the symptoms of allergy
without causing drowsiness. In sinus congestion, nasal sprays available on prescription provide
quick relief from symptoms of allergy.
Allergy shots prevent the allergen from being recognized as a foreign body. This treatment
is becoming very popular. Sublingual drops also known as sublingual Immunotherapy (SLIT) is an
alternate to allergy shots and has the same principle of desensitization. Oral application of SLIT is
also considered convenient by the patients.
Those interested in alternative medicine often recommend several alternate therapies.
Dietary supplements are said to increase health of immune system and prevent allergies. The other
alternative medicines are beyond the scope of this paper. [Allergies, 2006a] provides several
references to alternative treatment websites.
Anaphylaxis must be considered a medical emergency and immediate medical help must be
sought as it can cause low blood pressure, hyper-constriction, coma and even death.
The best prevention is to avoid the allergen responsible for causing the allergy. Cross the counter
medicine approved by a patients physician may also be used before coming into contact with
allergens. In view of the number of sufferers, various equipments such as vacuum cleaners,
humidifiers, beddings and air purifiers are available in the market to control domestic allergens. A
physician may be able to advice about prevention methods about other specific allergies.
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