How Allergic Reactions Work
Simple allergic reactions involve an
allergen (Ragweed, dust mite, cat, etc) finding
an antibody in the
nose, mouth, or throat, creating antigen-antibody
complexes. This triggers the immediate release of histamine
which causes congestion, itching, etc.
Less common allergic reactions
involve blood compliment pathways or fixed tissue reactions. These are often delayed in onset, prolonged in duration,
and are more likely to involve parts of the body other than the nose, throat, and lungs.
Mild allergic reactions are usually treated symptomatically with
antihistamines or nasal sprays. As allergic reactions get worse and interfere
more with daily life, the need to identify the offending allergens
becomes greater and treatment becomes more complicated. At that point, desensitization to the offending antigens might be considered.
Allergy testing is usually done either as a skin
test. Skin testing involves placement of
a small amount of allergen in the skin of the arm or back, creating small
wheals (bumps). These are observed for 10 minutes and
the change in size and color is recorded.
The acute reactions that go away within a few hours with the exception of molds, which can create acute and/or delayed reactions. Delayed
mold reactions, usually dark red bumps that occur 24-72 hours after
the skin test was placed, are often important. Notify your allergist
if you note delayed reactions to skin tests that were placed one
or more days earlier.
When you are scheduled for skin testing,
Wear a short sleeved shirt. Make sure you have been off all drugs
that might interfere with skin testing for an adequate period of
time. This includes antihistamines and other medications with an anticholinergic effect on the body including some antidepressants and certain
anti-acid stomach medications. Ask about your current medications
when scheduling your appointment for skin testing. Do not arbitrarily stop
antidepressants. Check with the doctor who put you on antidepressants before changing those
medications and make sure to let the doctor know if you are on a beta blocker for any reason. Skin testing is not usually done on someone on a beta blocker.
RAST is a blood test that checks for IgE levels of antigens in the blood. It is great for dust mites, cat, and multiple anaphylasis creating food allergens like egg, shrimp, and nuts. It is not accurate for testing most molds, possibly because mold reactions are not always IgE mediated. (even though symptoms from those mold reactions can be controlled sith desensitization.
Ignore the symptoms. This is fine if the
allergic problem is minimal in nature.
Avoid the offending
allergens. This is accomplished by cleaning up the
environment for allergens and avoiding places where allergens occur
For Pollen: Close windows to keep pollen out and
stay indoors as much as possible. Use air conditioning, both in
you home and car. Participate in outdoor activities when the pollen
counts are lowest.
For Dust Mites: Steam clean carpeting. Replace
old or musty carpeting. Use a central vacuum or a regular vacuum
with a HEPA filter. Wash pillows, sheets/pillowcases, comforters,
bedspreads, stuffed animals, and clothing regularly-- 130ºF
soapy water kills mites best. Do not leave piles of previously
worn clothing in the bedroom. Cover mattresses and pillows with
mite-impermeable covers. Clean out furnace ducts-- place filters
over vents in the bedroom especially. Avoid fabric headboards and fancy drapes that require drycleaning.
For Mold: Fix leaky roofs or plumbing. Fix leaky
showers and repair/replace moldy walls around showers, tubs, and
toilets. Flush out overflow drains for sinks and tubs with bleach.
Clean out the drain pan for the self-defrosting refrigerator.
Make sure water drains away from your house adequately. Use a
dehumidifier in the basement. Hose down concrete areas with dilute
bleach or borax. Store items in plastic bins instead of cardboard
boxes. Avoid using swamp coolers to decrease the temperature in
your house. Dry out the mold in your automobile air conditioning
ducts by turning the heat on high for a few minutes before getting
in the car and then switching to air conditioning. Avoid
dryer sheets and complicated cleaning chemicals. Decrease mold/yeast
containing foods in the diet.
For Animals: Bathe pets regularly; give them away
if absolutely necessary. Wash with animal shampoo. For cats, Dawn
dishwashing liquid can be used to wash most cats. Keep animals
out of bedrooms. Avoid sleeping with them.
Cleaning up the environment for
allergens takes a fair amount of time and effort, but it is worthwhile.
3. Use antihistamines with or without decongestants.
They prevent/decrease tissue swelling from occurring with an
allergic reaction. The newer ones are non-sedating. Regular use
is required for best. Remember: The
use of sedating antihistamines when driving a car is as dangerous as drinking
alcohol and driving!! There are only a few antihistamines
that are considered to be TRULY non-sedating by the FDA. They include fexofenadine and loratadine.
4.Use Cortisone products. Corisone
block the allergic reaction in a different way from antihistamines.
Pill and spray forms are used to treat nose, throat, and lung allergic reactions.
Sprays are not generally absorbed systemically, so they are quite
safe for nasal or pulmonary use. They usually require regular use to obtain maximum benefits.
Systemic cortisone use usually
has significant risks only if used for more than several weeks.
The rare, random, serious risks of cortisone use, like aseptic necrosis
of the hip, can occur after only one dose of a systemic cortisone product.
5. Allergy shots. Desensitization
involves having small amounts of the allergens to which a person
is allergic injected into the fat of the arm in slowly increasing
doses, causing the body to develop a tolerance to these allergens.
Starting with a small dose that has been deemed to be low enough
so as not to cause a reaction, the dose is increased gradually over
several months. During that time, symptoms generally diminish slowly.
Treatment is usually necessary for several years (3-10). Shots start
at 1 week intervals and gradually are stretched to 3-4 week intervals.
The improvement in symptoms and quality of life is generally worth
the effort and expense. Patients who have such diseases as chronic
sinusitis that has required one or more surgeries generally require
desensitization for optimal control. Because there is always a risk
of an adverse reaction to any allergy shot (including asthmatic
or anaphylactic reactions), a 20-30 minute wait in the office is
required after the allergy shot. Shots may be administered in the
office of the allergist or the office of most family physicians.