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When
someone has anaphylaxis, symptoms can start in different parts of the body
at the same time, including rashes, swelling of the lips and throat,
difficulty breathing and a rapid fall in blood pressure and loss of
consciousness. It occurs when there is a generalised release of a
substance called histamine from tissue cells called mast cells.
The incidence of anaphylaxis
appears to be increasing. The number of hospital admissions due to anaphylaxis doubled between
1991 and 1994 and increased seven-fold between 1994 and 2003.
Whilst this gives evidence of the increase in severe reactions, the figures only cover a proportion
of cases of anaphylaxis, not all of which need admission following emergency treatment. Some
cases are caused by wasp or bee stings,
some cases are caused by drugs or general
anaesthetics, and there are a few less common causes such as
allergy to rubber latex.
Anaphylaxis is also the
most serious form of true food
allergy; a few deaths occur each year from this cause.
Sufferers of all but the mildest variety of
food allergy, and those who have suffered from a
severe allergic reaction to wasp or bee are
therefore usually advised to carry an adrenaline
(epinephrine) injection
for self administration should the need arise.
In the UK and
Europe, peanuts, milk, eggs and fish are the most common foods to cause
anaphylaxis. Nuts, sesame seeds and shellfish can also cause it. The symptoms of anaphylaxis can start within seconds of eating the food,
but symptoms, may more commonly symptoms start minutes, or even an
hour or two later. Mild symptom may start off a reaction, with more severe
symptoms such as severe breathing difficulty, or collapse with low blood
pressure, developing up to several hours later. So anaphylactic reactions
can be mild to begin with, and more severe later. People with severe
allergies who also have asthma are at a greater risk of a severe reaction.
Anaphylaxis
is the most severe form of allergy and can be life threatening. Typically there is a dramatic,
rapid and diverse occurrence of any combination of the following symptoms, all of which are known to be associated with
severe allergy:
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Feeling of
faintness or unexplained apprehension
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Sensation of
irritation and/or restriction in throat
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Swelling of
mouth, lips, tongue
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Itchy rash or
tingly swellings anywhere on body
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Difficulty with
breathing, talking or swallowing
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Cough and/or
wheeze
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Blue lips, loss
of consciousness
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Breathing stops,
pulse stops, heart stops beating
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If severe, an attack may be accompanied by asthma, laryngeal
oedema (throat swelling or narrowing), fainting or collapse (blood pressure falls). A good
working definition of anaphylaxis (there is no generally accepted standard definition) is that it
should include at least one of the two potentially severe problems; breathing difficulty (due to
asthma or throat narrowing) and fall in blood pressure (fainting collapse or loss of
consciousness). Egg, fish,
peanut and other tree nuts (such as brazil nut), have been
noted for their ability to provoke severe reactions. The risk factors for anaphylaxis may
include history of a previous severe reaction to a food and a history of asthma especially if poorly
controlled.
Anaphylaxis
risk management
It is the advice of the
Department of Health in the UK that all patients who have suffered from anaphylaxis should be
seen in an allergy clinic.R
People
who are regarded as at risk of anaphylaxis (often because they have had a previous attack) should
ensure that they have this risk assessed and that an attempt has been made to properly identify the
cause.
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Most
cases of food-related fatal anaphylaxis occur outside the home
and are often associated with a failure to get the sufferer to
lie horizontal, if necessary with legs raised. Delay in
the administration of adrenaline is another risk factor.
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The
need to carry an adrenaline auto-injector (e.g. EpiPen®) in case of a
further attack needs to be assessed, this treatment will be advisable in
most established cases of anaphylaxis, although there may be some cases in
which adrenaline is not recommended.
However,
where there is a real risk that a further serious reaction might occur, this treatment will
normally be advised. Where the item responsible for triggering anaphylaxis is clearly
known, the ease with which the particular item can be safely avoided needs to be taken into
account when assessing the requirement to carry adrenaline.
Causes of anaphylaxis
Not all
anaphylaxis is caused by foods. Drugs, anaesthetics, bees & wasps and rubber
latex are known to cause the condition. In a proportion of cases, no allergic trigger can
be identified in spite of extensive investigation.
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Foods
and food additives
Those most often involved are nuts,
fish,
shellfish,
egg,
milk,
soya and
wheat. These foods
account for over 90% of cases in which foods are found to be involved. When anaphylaxis has no clear cause, it is often
wondered whether food additives, for example sulphites, may be responsible.
However, although this explanation is sometimes suspected, it is not often proven.
When a particular food is the cause of anaphylaxis, symptoms usually begin 5-30 minutes
after ingestion, but occasionally 1-2 hours after. Any food eaten earlier than
this is unlikely to be the cause. Even so, patients will very commonly suspect a
particular food or foods, even when the interval has been far longer.
Although it
is very important indeed that foods that have previously caused anaphylaxis should be
excluded, the avoidance of a range of foods that have no connection with the problem
will inevitably make things difficult in future. For this reason it is important
that such patients have appropriate investigations carried out at an allergy clinic.
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Drugs
and medicines
A wide range of drugs, and especially penicillins, similar antibiotics, anaesthetic drugs,
intravenous infusion solutions, radio-opaque dyes used for X-rays, and the group of
painkillers called NSAIDs (non-steroidal anti-inflammatory drugs), can occasionally
cause anaphylaxis. Any drug taken within a few hours of an attack of anaphylaxis
attack should be carefully noted.
Drugs called beta-blockers, used for heart
disease or
high blood pressure, can change mild reactions from another cause into severe anaphylaxis
because they block part of the natural defence against anaphylaxis. Heart or
blood-pressure drugs called ACE-inhibitors are commonly associated with angioedema,
although if anyone suffering anaphylaxis is taking such a drug it should be switched to
an alternative. Not infrequently, attacks may stop once this change is made.
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Rubber
latex
The natural latex, the main raw ingredient of rubber, is present in rubber gloves,
balloons, elastic, many medical products, and in many
things encountered in daily life. Sufferers are nearly often health care workers,
mainly nurses, or have other occupational contact with latex. They may get anaphylaxis
from bananas, avocados, kiwi fruit, figs, or other fruits and vegetables including even
potatoes and tomatoes.
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Bee
and wasp stings
Allergic reactions to bee and wasp stings are not uncommon, although the severe form
'anaphylaxis' is, thankfully, rare. Allergy is thought to be the explanation when when a sting causes
faintness or collapse, a difficulty in breathing caused by wheeze or throat swelling, a generalised rash or a swelling in a part of the body which
has not been stung. A large swelling (even up to the size of a plate) in the part of your body
which was stung is not a sign of allergy. It is not true that if you have had one
allergic reaction to a bee or wasp, that the next is certain to be more severe. It
quite likely that it will be the same and just as likely that no allergic reaction will
occur. In only one case in ten will it be more severe.
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Exercise
Exercise can act as a trigger for anaphylaxis with or
without exposure to an allergen often a food.
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Unknown
About a fifth of all sufferers of anaphylaxis have attacks that are completely unexplained
by an allergy. Doctors call such
unexplained attacks idiopathic anaphylaxis. Idiopathic means quite
simply that the cause is unknown. Experts believe that these cases have a disorder of the certain cells
of the immune system and that this abnormality makes them trigger-happy. Sufferers
may be interested to read an excellent short book about the condition
idiopathic
anaphylaxis (see below).
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Wrong
diagnosis
A proportion (about 10%)
of people sent to specialists with a diagnosis of anaphylaxis have a mistaken diagnosis
and have not had anaphylaxis. It is obviously essential to clarify the correct
diagnosis for such patients as they may be spared unnecessary fear and wrong treatment.
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Emergency
treatment
There
are two kinds of severe allergic reaction in that may require urgent medical
treatment.
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Anaphylaxis
(allergic collapse)
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Laryngeal
oedema
(allergic collapse)
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It
is possible for these reactions to occur together. Urgent medical treatment may be
needed for either condition, depending on the severity of the reaction (see below). The
distinguishing features of the two conditions are as follows.
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Anaphylaxis
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Laryngeal
oedema
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Anaphylaxis
is
the most severe form of allergic reaction and it is rare.
It usually occurs in someone already known to be allergic either to a
stinging insect (wasp or bee) or to a food (e.g. peanut, other nut, seafood) but
can also occur without prior warning.
These
symptoms are typical:
Feeling of
faintness
Severe
apprehension
Swelling of
mouth, lips, tongue or throat
Rash or
swellings anywhere on body
Difficulty with
breathing, talking or swallowing
Cough and/or
wheeze
Blue lips, loss
of consciousness
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Laryngeal
Oedema can result from an allergic reaction to a sting (e.g. bee or wasp) or from eating
a food (e.g. nut, seafood) if the individual is highly allergic to
it. It is, thankfully, rare even
amongst those with bee or wasp sting allergy or immediate food allergies.
These
symptoms are typical:
Feeling
of a severe lump in the throat
Feeling
that the throat is narrowed
Choking
sensation Breathing
becomes laboured Breathing
becomes noisy Harsh sound from the throat or whistling from the chest)
Lips
may become blue (signifying obstruction to the oxygen supply)
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The importance of
adrenaline
Not
only is failure to carry adrenaline a risk factor for a patient with a severe anaphylaxis
risk, so to is failure to use it when the situation requires it.  The
EpiPen® device is easy to use, but it is important that those who need it have been shown
not only how to use it, but precisely when to use it. Your GP, practice nurse or allergy
clinic can advise. For a website containing an animated demonstration of how to use the EpiPen click on the
box right.
Support and advice for anaphylaxis sufferers
Adequate education and support for sufferers of anaphylaxis is vital if they
are to lead normal lives and remain free of risk. Allergy clinics provide an important
role in identifying the cause of reactions where this is unknown. They can also advise
on when sufferers need to be equipped with self-injectable adrenaline (see below). In
addition, excellent support and information is also provided by the Anaphylaxis
Campaign (www.anaphylaxis.org.uk)
and anyone who suffers from any type of severe allergy should enquire about
membership.
School
children with anaphylaxis
The management of
anaphylaxis in school children creates a particular problem, as proper communication and the
setting up of precautionary measures needs to be arranged between parents, schools, teachers,
doctors and education authorities. Affected children are, with extremely few exceptions,
managed in mainstream schools. Information
for Schools
is provided on the Anaphylaxis Campaign website.
Food-dependent
exercise-induced anaphylaxis
 This
is an unusual condition where someone has an allergic reaction when they
exercise within an hour or two of eating an allergy-inducing food. People
who are sensitive in this way can usually eat the food if they do not
exercise immediately afterwards with either a very mild reaction, or no
reaction at all. However they can experience a severe reaction (including
anaphylaxis) if they eat it just before exercise.
The commonest identified cause is wheat,
and normally a skin-prick test will confirm this. Other foods that
have been blamed include celery, shrimp/prawn, apple, squid, abalone,
hazelnut, grape, egg, orange, cabbage and chicken.
In
other rare cases, anaphylaxis appears simply to follow exercise, without
any evidence that the sufferer has been exposed to an allergen.
Experts
don’t fully understand why some people react in this way.
Support Organisations
The
Anaphylaxis Campaign
www.anaphylaxis.org.uk
This organisation provides an extremely valuable service to its members both by providing help-line
support, an excellent regular newsletter, and the representing the interests of patients with
severe food and other allergies in discussions both with politicians and the food
industry. All those who have suffered anaphylaxis or severe laryngeal oedema are advised
to become members of this excellent organisation.
The
MedicAlert® Foundation
This the only non-profit making, registered charity providing a life-saving identification
system for individuals with hidden medical conditions and allergies. This takes the form of
body-worn bracelets or necklets bearing the MedicAlert® symbol on the disc and
supported by a 24 hour emergency telephone service. Each member receives an Emblem that is
engraved with the wearer’s main medical condition(s) or vital details, a personal ID number
and a 24 hour emergency telephone number that can access their details from anywhere in the
world in over 100 languages.
The
MedicAlert
Foundation
1
Bridge Wharf
156 Caledonian Road
London
N1 9UU
Telephone: 0800 581 420
Email:
info@medicalert.org.uk
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Recommended Websites
Anaphylaxis Campaign
A valuable organisation that deals with the concerns and needs of all who suffer from
anaphylaxis or laryngeal oedema. They produce a useful regular newsletter.
www.anaphylaxis.org.uk
Administering
adrenaline - EpiPen and Anapen demo
The website provides information about severe allergic reactions and the use of the
EpiPen. The device is described in detail and clear instructions concerning its use are
provided.
EpiPen
and Anapen demo
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