Allergies
Allergies are hypersensitive responses from
the immune system to substances that either enter or come into contact with the
body. These substances commonly include materials such as pet dander, pollen,
or bee venom. Anything can be an allergen if the immune system has an adverse
reaction. A substance that causes an allergic reaction is called an allergen.
Allergens can be found in food, drinks, or the environment. Many allergens are
harmless and do not affect most people. If a person is allergic to a substance,
such as pollen, their immune system reacts to the substance as if it was
foreign and harmful, and tries to destroy it. Research indicates that 30
percent of adults and 40 percent of children in the United States have
allergies.
Allergy Symptoms
An
allergic reaction typically triggers symptoms in the nose, lungs, throat,
sinuses, ears, lining of the stomach or on the skin. For some people, allergies
can also trigger symptoms of asthma. In the most serious cases, a
life-threatening reaction called anaphylaxis (an-a-fi-LAK-sis)
can occur.
A
number of different allergens are responsible for allergic reactions. The most
common include:
·
Pollen
·
Dust
·
Food
·
Insect
stings
·
Animal
dander
·
Mold
·
Medications/Drugs
·
Latex
Common allergies
Substances
that cause allergic reactions are called allergens. The more common allergens
include:
·
grass
and tree pollen – an allergy to these is known as hay fever (allergic rhinitis)
·
dust
mites
·
animal
dander (tiny flakes of skin or hair)
·
food
– particularly nuts, fruit, shellfish, eggs and cow's milk
·
insect
bites and stings
·
medication
– including ibuprofen, aspirin, and certain antibiotics
·
latex
– used to make some gloves and condoms
·
mould
– these can release small particles into the air that you can breathe in
·
household
chemicals – including those in detergents and hair dyes
Most
of these allergens are generally harmless to people who aren't allergic to
them.
Causes
A
particular antibody called immunoglobin (IgE) causes allergic reactions. Antibodies are released to
combat foreign and potentially harmful substances in the body. IgE is released to destroy the allergen and causes the
production of chemicals that trigger the allergic reaction. One of these
chemicals is called histamine. Histamine causes tightening of the muscles in
the airways and the walls of blood vessels. It also instructs the lining of the
nose to produce more mucus.
Risk factors
The
following can be risk factors for developing allergies:
·
a
family history of asthma or allergies
·
being
a child
·
having
asthma
·
not
being exposed to enough sunlight
·
having
a different allergy
·
birth
by Caesarean section
Diagnosis
The
doctor will either recommend some tests to find out which allergen is causing
symptoms or refer the patient to a specialist.
Below
are some examples of allergy tests:
Blood test: This measures the level of IgE antibodies released by the immune system. This test is
sometimes called the radioallergosorbent test (RAST)
Skin prick test: This is also known as puncture
testing or prick testing. The skin is pricked with a small amount of a possible
allergen. If the skin reacts and becomes itchy, red, and swollen, it may mean
an allergy is present.
Patch test: A patch test can identify eczema.
Special metal discs with very small amounts of a suspected allergen are taped
onto the individual's back. The doctor checks for a skin reaction 48 hours later, and then again after a couple of days.
Treatment
Generally,
antihistamine medications are the treatment of choice after the allergen is
removed. Very severe reactions may require other therapy, such as oxygen for
breathing difficulties or intravenous fluids and/or epinephrine to boost blood
pressure in anaphylactic shock. Patients with very severe reactions usually
require hospitalization.
Medications
Drugs
can help treat the symptoms of an allergic reaction, but they will not cure the
allergy. The majority of allergy medications are over-the-counter (OTC). Before
taking a particular type of medication, speak to a pharmacist or doctor.
Antihistamines: These block the action of
histamine. Caution is recommended, as some antihistamines are not suitable for
children.
Decongestants: These can help with a blocked
nose in cases of hay fever, pet allergy, or dust allergy. Decongestants are
short-term medications.
Leukotriene
receptor antagonists, or anti-leukotrienes: When other asthma treatments
have not worked, anti-leukotrienes can block the
effects of leukotrienes. These are the chemicals that
cause swelling. The body releases leukotrienes during
an allergic reaction.
Steroid sprays: Applied to the inside lining of
the nose, corticosteroid sprays help reduce nasal congestion.