Allergies
DEFINITION
A person who is overly-reactive to a substance that is well
tolerated by most other people, is said to be allergic, or
atopic..
tolerated by most other people, is said to be allergic, or
atopic..
DESCRIPTION
The substance which causes an allergic reaction is called an
‘allergen’. An allergic reaction causes the immune system to
over-react to the substance. Antibodies are produced within the
body to identify and destroy allergens. Allergic reactions occur
when there is an overproduction of an antibody and the immune
defences act too strongly against an allergen. The antibody binds
to certain cells (mast cells) found mainly in the skin and lining
of tissues of the body such as in the nose, lungs and gut.
‘allergen’. An allergic reaction causes the immune system to
over-react to the substance. Antibodies are produced within the
body to identify and destroy allergens. Allergic reactions occur
when there is an overproduction of an antibody and the immune
defences act too strongly against an allergen. The antibody binds
to certain cells (mast cells) found mainly in the skin and lining
of tissues of the body such as in the nose, lungs and gut.
When an allergen is inhaled or eaten, the mast cell is
activated to release substances called mediators, such as
histamine, to combat the allergen. Histamine and other mediators
cause inflammation and tightening of the airways. Antihistamines
are drugs which help to block this reaction.
activated to release substances called mediators, such as
histamine, to combat the allergen. Histamine and other mediators
cause inflammation and tightening of the airways. Antihistamines
are drugs which help to block this reaction.
Intolerance vs allergy
Many food intolerances are mistaken for allergies. A food
intolerance is an adverse food-induced reaction that does not
involve the immune system. A food intolerance may cause symptoms
such as gastrointestinal problems (eg. diarrhoea or constipation.
Lactose intolerance, for example, is due to difficulty digesting
the sugar in milk and is also not an allergy.
intolerance is an adverse food-induced reaction that does not
involve the immune system. A food intolerance may cause symptoms
such as gastrointestinal problems (eg. diarrhoea or constipation.
Lactose intolerance, for example, is due to difficulty digesting
the sugar in milk and is also not an allergy.
CAUSE
Most allergens are found in the atmosphere and may include
cigarette smoke, dust, pollen etc. Other allergens include food,
insect stings, medications and latex; in fact anything which the
body may regard as ‘foreign’.
cigarette smoke, dust, pollen etc. Other allergens include food,
insect stings, medications and latex; in fact anything which the
body may regard as ‘foreign’.
There are 4 main types of allergens. These typically
include:
include:
Inhalants
- House dust mites
- Other components of house dust such as food materials and
fragments from insects - Pollens from grasses and weeds (causing hayfever)
- Spores from moulds
- Cigarette smoke
- Air pollution
- Animal hair/fur
Foods
- Cow’s milk
- Wheat
- Eggs
- Nuts
- Seafood
- Soya beans
- Drugs such as penicillin
- Naturally occurring or added food chemicals, such as
salicylates, amines and glutamates. See the Food allergies topic on
Healthpoint.
Injectants
- Insect bites or stings
- Injections of antibiotics (the most common being penicillin)
and vaccines. A more serious allergic reaction called anaphylaxis
may occur which can be fatal if not treated promptly.
Contact allergens
- Allergies occur when the following come in contact with the
skin: - Plants
- Industrial chemicals and those used in handiwork and other
hobbies such as glues and solvents - Some cosmetics
- Jewellery.
SIGNS AND SYMPTOMS
Whenever an allergic reaction occurs, there is tissue (cell)
injury. Depending on the allergen and where it enters the body
different symptoms may be experienced. Pollen, for example, when
breathed in through the nose, may cause symptoms in the nose, eyes,
sinuses and throat. Anaphylaxis is the most severe form of allergic
reaction. It results in potentially life-threatening symptoms such
as difficulty breathing, hives, stomach upset or a drop in blood
pressure (shock).
injury. Depending on the allergen and where it enters the body
different symptoms may be experienced. Pollen, for example, when
breathed in through the nose, may cause symptoms in the nose, eyes,
sinuses and throat. Anaphylaxis is the most severe form of allergic
reaction. It results in potentially life-threatening symptoms such
as difficulty breathing, hives, stomach upset or a drop in blood
pressure (shock).
General allergy symptoms
- Nasal congestion
- Coughing
- Wheezing
- Itching
- Shortness of breath
- Headache
- Fatigue
- Hives and other skin rashes.
- Food allergy symptoms
- Swelling of the tongue and throat
- Difficulty swallowing
- Nasal congestion
- Difficulty breathing
- Runny or itchy nose (rhinitis)
- Hives or skin rash
- Vomiting
- Abdominal cramps
- Diarrhoea
- Wheezing (this often sounds like the wheezing associated with
asthma) - In severe cases: drop in blood pressure, loss of consciousness
and respiratory failure (anaphylactic shock).
TREATMENT OPTIONS
It is important to consult your Doctor to diagnose and treat
this ailment. Food and chemically-induced allergies can be
difficult to identify. Your doctor may refer you to an allergy
specialist to identify the cause. This specialist can accurately
diagnose an allergy by a blood test or skin prick test. The
severity of the allergy is assessed according to the test result
and the person’s clinical history.
this ailment. Food and chemically-induced allergies can be
difficult to identify. Your doctor may refer you to an allergy
specialist to identify the cause. This specialist can accurately
diagnose an allergy by a blood test or skin prick test. The
severity of the allergy is assessed according to the test result
and the person’s clinical history.
DIET HINTS
Note: Allergic responses to certain foods can cause very
serious symptoms. It is essential to identify allergenic foods so
other more serious problems do not arise. Your doctor may refer you
to an allergy specialist.
serious symptoms. It is essential to identify allergenic foods so
other more serious problems do not arise. Your doctor may refer you
to an allergy specialist.
- Avoid foods that are most commonly associated with allergic
reactions, such as peanuts, cow’s milk, soya, seafood and eggs.
Similar reactions can occur to some chemicals and food
additives. - Fortunately, the majority of food allergies are not severe, and
will disappear with time, particularly in children. Allergies to
nuts, seeds and seafood, however, tend to persist throughout
life. - In some cases, a temporary ‘elimination diet’ under close
medical supervision will be needed. Potentially allergic foods are
eliminated from the diet then reintroduced to help identify the
cause of the allergic reaction. - Carefully read the content labels of foods in supermarkets. For
example, the terms ‘whey’ or ‘casein’ would indicate the presence
of dairy products. - Prepare in advance for eating away from home as this poses
greater risks. For example, it is wise to inform your host or
restaurant chef about your allergy and the importance of avoiding
contamination of your meal with an allergen. - It is important to discourage a child with a food allergy from
swapping food with friends. - You may need to provide special party food for your allergic
child to take to parties. - Relatives, baby-sitters and other caregivers need to be warned
about the problem.
PREVENTION
Avoid house dust by replacing carpet with polished boards,
linoleum, cork or slate; vacuuming regularly, storing books and
dust catching items out of living areas and replacing curtains with
plastic blinds.
linoleum, cork or slate; vacuuming regularly, storing books and
dust catching items out of living areas and replacing curtains with
plastic blinds.
Watch for allergic reactions to pets, especially cats.
Remember that cat saliva which is an allergen, remains suspended in
the air for up to six months.
Remember that cat saliva which is an allergen, remains suspended in
the air for up to six months.
See the anaphylactic shock section on Healthpoint for
information about severe allergic reaction.
information about severe allergic reaction.
ORGANISATIONS & SUPPORT GROUPS
Anaphylaxis Australia
21 Robinson Close
Hornsby Heights
NSW, 2077
Australia
Ph: 1300 728 000
Email: coordinator@allergyfacts.org.au
Website: www.allergyfacts.org.au
PHARMACIST’S ADVICE
- Try to identify the source of the problem and make every effort
to avoid any known allergens. - Your pharmacist may suggest an antihistamine. Ask about any
possible side effects, which may include drowsiness. Tell your
pharmacist if you are pregnant or breastfeeding. . - If the allergy has caused a rash and the skin is not broken,
ask your pharmacist for an antihistamine or mild steroid
cream. - If you suffer from pollen inhalation, consider staying indoors
between the hours of 6 am and noon, when pollen is at high levels
in the atmosphere. Wearing a mask and sunglasses while mowing or
working in the garden may provide protection while you are working
in the garden.
