Spreading Allergy Awareness
Allergists define allergy as a reaction of the body's immune system that take place after the body becomes sensitized to a substance (allergen), usually a protein. Allergic reactions result when allergy-causing proteins combine with antibodies to trigger the release of histamine and other chemicals that can cause skin rashes and various other symptoms
Types of Allergy
Allergies come in a wide variety. They are often classified according to where they produce symptoms: skin, respiratory tract (nose, lungs). Or their causes: insect stings, foods, medicines.
Allergies to insect stings
- Allergies to medicine
Causes of Allergy
There is a genetic component to most allergies, which means allergies are hereditary and passed to children from their parents. The child inherits the tendency to be allergic, but not to any specific allergen. If a child develops an allergy, it is likely that at least one parent of the child also has allergies. Another risk factor that appears to contribute to the development of allergy is the act of being exposed to allergens at certain times when the body's defenses are low or weak, such as after a viral infection or during pregnancy.
The substances that cause allergic disease are known as allergens. They enter our bodies in a variety of ways:
Inhaled into the nose and the lungs: Examples are: airborne
pollens of certain trees, grasses and weeds, dust mite droppings, mould
spores, cat and dog dander
Ingested by mouth: These are generally the things that we eat and
drink, including prawns and peanuts
Injected: Such as reactions to stinging insects and injectable
Absorbed through the skin: Things we come into contact with:
poison ivy, oak and cosmetics
The normal reaction of our body to invasion by foreign substances is to
defend itself. This is the role of our immune system.
To find the cause of an allergy, needs considerable diagnostic skills,
otherwise a lot of money and time can be spent looking in the wrong direction
before you get to the correct answer.
Symptoms of Allergy
When an allergen enters the body of a person with a sensitized immune system, histamine and other chemicals are released by certain cells. This causes itching, swelling, mucus production, muscle spasms, hives, rashes, and other symptoms.
There is no single allergy symptom, they vary with the source and type of
Symptoms can include:
tearing eyes, burning or itching eyes
itching nose, mouth, throat, skin, or any other area
hives (skin wheals)
How is allergy diagnosed or
A carefully obtained patient history, including environmental exposures, and the appropriate laboratory tests or allergen challenges is critical for the accurate diagnosis of allergy.
Tests that may reveal the specific allergens include:
Skin testing -- the most common method of allergy testing. This
may include intradermal, scratch, patch, or other tests. Skin testing may
even be an option for young children and infants, depending on the
test -- also called RAST (radioallergosorbent), this measures the levels
of allergy antibody, IgE, produced when your blood is mixed with a series of
allergens in a laboratory.
If you are allergic to a substance, the IgE levels may increase in the blood
sample. The blood test may be used if you have existing skin problems like
eczema,, if you're on medications that are long-acting or you cannot
stop taking, if you have a history of anaphylaxis, or if you prefer not to
have a skin test.
"Use" or "elimination" tests -- suspected items are eliminated
and/or introduced while the person is observed for response to the
substance. This is often used to check for food or medication allergies.
Eyelid -- Occasionally, the suspected allergen is dissolved and
dropped onto the lining of the lower eyelid (conjunctiva) as a means of
testing for allergies. (This test should only be done by a physician, never
the patient, since it can be harmful if done improperly.)
- Reaction to physical stimuli -- application of heat, cold, or other stimulation, and then look for an allergic response.
Other tests that may reveal allergies include:
(particularly IgE) levels -- when these are elevated, it indicates a
"primed" immune system.
Complete Blood Count (CBC) -- may reveal an increase in eosinophils. The
results can reflect problems with fluid volume (such as dehydration) or loss
of blood. It can show abnormalities in the production, life span, and rate
of destruction of blood cells. It can reflect acute or chronic infection,
allergies, and problems with clotting.
Complement levels -- may be abnormal.
There are three techniques commonly offered by doctors to help allergy sufferers:
Many allergens, once identified, can simply be avoided. If you know you're
allergic to shellfish, you don't eat it. Pet allergies can be handled sometimes
by keeping the pet outside.
Unfortunately, many allergens -- like pollen, mold and dust -- are very difficult, if not impossible, to avoid. These can often be managed by using medications such as antihistamines, decongestants, cromolyn sodium, corticosteroids and, in the case of anaphylaxis, epinephrine.
Medications that can be used to treat allergies
include the following:
- Short-acting antihistamines, which are generally non-prescription, often relieve mild to moderate symptoms but can cause drowsiness. In addition, these antihistamines can blunt learning in children (even in the absence of drowsiness). An example is diphenhydramine. One formerly prescription medication, loratadine (Claritin), is now available over the counter. It does NOT tend to cause drowsiness or affect learning in children.
Longer-acting antihistamines cause less drowsiness and can be equally
effective, and usually do not interfere with learning. These medications,
which require a prescription, include fexofenadine (Allegra) and cetirizine
Nasal corticosteroid sprays are very effective and safe for people with
symptoms not relieved by antihistamines alone. These prescription
medications include fluticasone (Flonase), mometasone (Nasonex), and
triamcinolone (Nasacort AQ).
Decongestants may also be helpful in reducing symptoms such as nasal
congestion. Nasal spray decongestants should not be used for more than
several days, because they can cause a "rebound" effect and make the
congestion worse. Decongestants in pill form do not cause this effect.
Cromolyn sodium is available as a nasal spray (Nasalcrom) for treating
hay fever. Eye drop versions of cromolyn sodium and antihistamines are
available for itchy, bloodshot eyes.
Leukotriene inhibitors -- montelukast (Singulair) is a prescription medicine approved to help control asthma and to help relieve the symptoms of seasonal allergies.
Immunotherapy is expensive, time consuming and not without risk. But it is often the only hope a person has for leading a normal life. It consists of a series of injections of the offending allergen, beginning with a very weak dilution and gradually building in strength to a maintenance dose that may be continued over time. The injections help the immune system to produce fewer IgE antibodies, while also stimulating the production of a blocking antibody called IgG. This works to varying degrees with many allergies, but some cannot be treated this way.