Allergic reactions rarely occur
the first time we take a
medication,
it
requires
exposure to the drug to develop
the
immune
response,
therefore most severe reactions
will occur with subsequent
doses. (3, 5). These occur not
only
with
prescribed
medications but also natural
products.
Symptoms of allergy can be as
mild as hives, rash, itchy skin or
on the more severe end of the
spectrum the symptoms can
include swollen face, throat
tightness, trouble breathing,
light-headedness,
blisters,
reddened skin or whole-body
shock with life-threatening low
blood pressure (1,5,10).
Beware, the pseudo allergic
reactions, these mimic those
caused by IgE antibodies but are
not initiated by IgE, these occur
as a result of histamine release
and
other
non-immune
mechanisms and these can
occur the first time a drug is
taken. These are as potentially
life-threatening as a true
allergic reaction; the symptoms
and the treatment are the same
for both. The most common
drugs
involved
include:
morphine, opiates, anaesthetic
muscle relaxants and contrast
media. Non-steroidal drugs and
aspirin have been noted to
cause urticaria and asthma and
Spring 2019
L.O.G.I.C
anaphylaxis in
people. (3, 8).
susceptible
There are two allergy response
types:
Rapid onset within 1-2 hours of
ingestion, this is IgE mediated.
This is the one which needs
immediate attention as the
symptoms include: abdominal
pain,
confusion,
urticaria,
wheezing,
hoarse
voice,
dizziness or fainting, rapid pulse
and/or heart palpitations,
angioedema,
bronchospasm
and anaphylaxis. (5, 6)
Delayed onset which often
occurs with antibiotics, this is
IgG mediated. Can occur up to
10
days
after
initiating
treatment and the main
symptom is rash. The confusing
factor with this is that the rash
may be related to the illness.
There are more serious delayed
immune reactions involving
rash in conjunction with
systemic symptoms including:
Serum Sickness-like reaction
(most commonly associated
with cephalosporins)
Stevens-Johnson
syndrome
(most commonly associated
with sulphonamides)
Asceptic Meningitis (most
commonly associated with
trimethoprim/co-trimoxazole)
(5, 6)
SIDE EFFECT:
These can seem like an allergic
reaction but in reality, is just a
sensitivity felt by the body to a
new medication and is not
immune
mediated.
(1,5)
According to the World Health
Organisation a side effect is an
unintended effect of a drug
occurring at a dose which is
normally used and is related to
the pharmacological properties
of the medication. (7)
Side effects are more common
than
allergy
but
often
misinterpreted and reported by
patients as an allergy.
The most common symptoms
include: nausea, lack of energy,
muscle aches, hard to sleep,
coughing, wheezing, stuffy
nose,
stomach
cramps,
diarrhoea, constipation, ringing
in the ears, easy bruising. (1, 5).
INTOLERANCE:
This is a sensitivity reaction to a
medicine which does not
involve the immune system. It is
dependent on two factors: the
pharmacological action of the
medicine and the patient
susceptibility factors. This
means that these people usually
have a low threshold for
developing adverse effects or
exaggerated side effects or
developing a side effect not
normally associated with the
medication. (6)
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