What does h/o drug allergy mean

Case study 2: treatment options in true allergy

Matthew Bonzer is a 30-year-old patient with a documented history of a penicillin allergy causing an itchy rash. He has been diagnosed with a bacterial respiratory tract infection. What treatment options can be considered?

Answer:

Chloe reports gastrointestinal disturbance.

What does h/o drug allergy mean

This is a known adverse drug reaction but is not a contraindication or true allergy. It is therefore likely that Chloe is intolerant of penicillins, but does not own a penicillin allergy and the medicines can be used safely if required.

Case study 1: assessing history of allergy

Chloe Monroe is a 47-year-old female admitted to hospital for treatment of possible diverticulitis.

What does h/o drug allergy mean

Chloe’s notes state that she is allergic to penicillin; the nature of the reaction is gastrointestinal disturbance and diarrhoea. On further questioning, she says she gets an “upset stomach” and diarrhoea when taking oral penicillins and will not ingest these medicines. Chloe says she does not experience any itchiness, rash, swelling or other symptoms when taking penicillin. Does Chloe own a penicillin allergy?

Answer:

Matthew has previously experienced symptoms of an allergic reaction to penicillins, therefore a non-penicillin drug should be chosen to treat the infection.

Clarithromycin is a macrolide antibiotic and is unrelated to penicillin, and the likelihood of the patient experiencing a reaction is low. He can therefore be started on clarithromycin to treat his respiratory tract infection.

Shilpa Jethwa MSc, MRPharmS, is a specialist pharmacist (antibiotics) at Northwick Park Hospital, London North West Healthcare NHS Trust.

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Citation: The Pharmaceutical Journal, 5 September 2015, Vol 295, No 7878, online | DOI: 10.1211/PJ.2015.20069170


Inadvertent istration

It is a medical emergency if inadvertent istration of penicillin in a patient with known penicillin allergy takes put.

The offending drug should be stopped immediately. Anaphylaxis should be treated with adrenaline injection and emergency care to maintain blood pressure and support breathing[34]. A second dose of adrenaline may be required in a little percentage of patients if there is insufficient response. More than two doses are rarely required[35].

Rashes or hives can be treated with an antihistamine such as chlorpheniramine, although more severe reactions may require treatment with oral or injectable corticosteroids.

The severity of the reaction will determine the dose, duration and formulation of treatment.

Following emergency management, patients require shut monitoring in hospital for 2–24 hours to ensure they do not develop biphasic anaphylaxis[36],[37],[38],[39]. Biphasic anaphylaxis is the recurrence of symptoms within 1–72 hours with no further exposure to the allergen[35].

The recurrence typically occurs within eight hours[37]and is managed in the same manner as anaphylaxis[40].

The risk of inadvertent istration of a medicine known to cause allergy can be minimised by ensuring the patient knows about their condition, and that an precise medical history is taken before the medicine is prescribed. In hospitals, every inpatients should own known adverse drug reactions included on every patient documents (e.g. drug charts, prescriptions, patient medication records and discharge summaries); this should include information on the nature of the reaction and when it occurred.

If inadvertent istration occurs, the incident should be reviewed to identify the reason and effective safety measures put in put to prevent recurrence[41].

Combination products should also be prescribed generically with their individual constituents to assist staff identify when a prescribed medicine may be inappropriate.


Treatment options

Patients who own experienced a type I allergic reaction with penicillins (e.g. urticaria, laryngeal oedema, bronchospasm, hypotension) should not be prescribed beta-lactam agents including penicillins, cephalosporins, carbapenems or monobactams[10],[23].

Cephalosporins and carbapenems can be used with caution in patients that do not own a history of a type I mediated allergic reaction. Cephalosporin allergy is largely dependent on the generation of cephalosporin used[23].

First generation cephalosporins (e.g. cefazolin) were believed to own a cross-reactivity rate of around 10% in patients with a penicillin allergy[23]. However, at the time of these early studies, cephalosporin formulations contained trace amountsof penicillin[23],[24],[25], so this figure is thought to be an overestimate.

What does h/o drug allergy mean

The true incidence of cross-sensitivity is unknown but there are data to propose that it is muchlower[25]. Second and third generation cephalosporins (e.g. cefuroxime, ceftriaxone, ceftazidime) own a lower propensity for cross reactivity, as they own diverse side chains to penicillin, which contribute to the decreased immunogenicity[26]. However, alternatives should be used wherever possible (see below).

Carbapenems (e.g. meropenem, imipenem, ertapenem, doripenem) own a cross reaction rate of 1–6%[27],[28] in patients who own previously suffered IgE-mediated reactions to penicillins.

What does h/o drug allergy mean

A thorough clinical history should be taken before prescribing this class of drugs to a patient with known or suspected penicillin allergy.

Aztreonam is a monobactam that does not contain a bicyclic-ring structure[29]similar to penicillins, cephalosporins and carbapenems. It can therefore be used safely in patientswith a history of penicillin allergy[23],[26],[30], unless the patient is known to be allergic to ceftazidime, which has an identical side chain to aztreonam[30],[31].

Tetracyclines (e.g. doxycycline), macrolides (e.g. clarithromycin), aminoglycosides (e.g. gentamicin), metronidazole, quinolones (e.g.

ciprofloxacin) and glycopeptides (e.g.

What does h/o drug allergy mean

vancomycin) are every unrelated to penicillins and are safe to use in patients with penicillin allergy. However, patients with penicillin allergy are more likely to react to any class of drug[10],[32],[33].


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Risk factors

Patients aged 20–49 years are at increased risk of anaphylaxis[9],[12], although the reasons are unknown.

There is no evidence to propose a hereditary link to anaphylaxis and therefore family history is irrelevant. Thelatest data propose there is no link between atopic disease (e.g. patients with asthma, eczema or hay fever) and increased risk of penicillin allergy[8],[9], although patients with atopic disease may experience more severe reactions.

Asmany as 85% of patients who previously reacted to penicillin may not react upon second exposure if the time interval from the final exposure is prolonged[9],[18],[19].

A clinical history of penicillin allergy in the more distant past (>15 years) is associated with only a extremely low risk (0.4%) of reactions[20], and only 20–30% of patients positive on a penicillin skin test remain positive after ten years[21].

An allergic reaction is most commonly seen after parenteral istration[10].

Less commonly, penicillin allergy reactions can happen days or weeks after exposure and may persist after treatment has stopped. Other conditions associated with penicillin allergy include serum sickness, drug-induced anaemia, drug reaction with eosinophilia and systemic symptoms (DRESS) and nephritis[10].


Assessment

The first step to assessing a possible penicillin allergy before a drug is prescribed is to take a detailed history (see ‘Questions to establish a penicillin allergy’)[7],[9].

Questions to establish a penicillin allergy

  • What other medications was the patient taking?

    Why and when were they prescribed?

  • What antibiotics has the patient taken and tolerated since the allergy diagnosis?
  • Did the reaction resolve on stopping the antibiotic? If so, what happened after stopping the drug?
  • Does the patient recall the reaction, and if not, who informed them of it?
  • What was the patient’s age at the time of the reaction?
  • How endless after beginning penicillin did the reaction occur?
  • What antibiotics has the patient reacted to in the past?
  • What was the nature of the reaction?
  • Did this reaction result in hospitalisation?
  • Why was the patient taking the antibiotic?
  • What was the route of istration?
  • If a rash was present then: a.

    Describe the nature of the rash (e.g. pustular, urticarial), b. Could the rash be related to an underlying condition (e.g. viral)? c. How endless after commencing the antibiotic did the rash appear?

  • Has the patient taken antibiotics similar to penicillin (e.g. amoxicillin, cephalosporins) before or after the reaction? If so, did anything happen?

Histories can be unreliable and can result in over diagnosis of allergy. Some patients may own been too young to fully remember the reaction and patients who report a vague history of symptoms or gastrointestinal intolerance are probably not truly allergic to penicillins.

Approximately 80–90% of patients reporting a penicillin allergy are negative when assessed by skin testing[7]. This test can aid in determining a patient’s allergy status and identifying those at high risk of penicillin reactions[10],[22].

If a patient reports a rash after ingestion or istration of a medicine containing penicillin, its type can be used to guide whether a related drug (e.g. a cephalosporin or carbapenem) can be used safely. Rashes that involve hives (raised, intensely itchy spots that come and go over hours), or happen with other penicillin allergic symptoms (e.g.

wheezing or swelling of the skin or throat)[7],[10] propose a true penicillin allergy. Rashes that are flat, non-itchy, develop over days and do not change in appearance are less likely to represent a dangerous allergy.

Histories can be unreliable and can result in over diagnosis of allergy. Some patients may own been too young to fully remember the reaction and patients who report a vague history of symptoms or gastrointestinal intolerance are probably not truly allergic to penicillins. Approximately 80–90% of patients reporting a penicillin allergy are negative when assessed by skin testing[7]. This test can aid in determining a patient’s allergy status and identifying those at high risk of penicillin reactions[10],[22].

If a patient reports a rash after ingestion or istration of a medicine containing penicillin, its type can be used to guide whether a related drug (e.g.

a cephalosporin or carbapenem) can be used safely. Rashes that involve hives (raised, intensely itchy spots that come and go over hours), or happen with other penicillin allergic symptoms (e.g. wheezing or swelling of the skin or throat)[7],[10] propose a true penicillin allergy. Rashes that are flat, non-itchy, develop over days and do not change in appearance are less likely to represent a dangerous allergy.



Duration of Hives

“A hive lesion doesn’t generally final much longer than 24 hours, whereas things love bug bites, which are easily confused with hives, can final several days,” Friedman says.

That means you might wake up with a hive one morning — and that one specific hive may be completely gone by the next morning, Friedman says. “And they often appear without any warning.”

Hives also move around, and they don’t necessarily care what body part they inhabit.

What does h/o drug allergy mean

Even your scalp, soles of your feet, and palms of your hands can get hives. “If you see one moving a lot, that signals a hive,” Friedman says.

RELATED: How to Identify Common Bug Bites and Stings

Acute hives final less than six weeks, while chronic hives final more than six weeks. That doesn’t mean you’re covered in hives every day during these time periods, but it does mean that during these time frames, the hives come and go either erratically or sometimes on a more consistent basis, says Anthony M.

Rossi, MD, an assistant attending dermatologist at Memorial Sloan Kettering Cancer Middle in New York City.

Fortunately, although they might itch a lot, hives don’t leave any marks on the skin once they vanish, regardless of whether you’ve treated them or not.

Hives are neither contagious nor, in most cases, dangerous. There are, however, a few exceptions that should immediate emergency care.

The first is a condition called angioedema, which involves swelling of the tissue beneath the skin. That can lead to swelling in the tongue, lips, throat, hands, feet, and even the inside of the abdomen.

As a result, people could own stomach cramps or worse, difficulty breathing. People with hives can own angioedema, but note that “just because you own hives doesn’t mean you’ll get angioedema,” Dr. Rossi says.

When hives are accompanied by swelling and breathing becomes hard, seek emergency care correct away.

Hives may also be the result of a serious allergic reaction called anaphylaxis, Rossi says. If you experience difficulty breathing; swelling of your lips, tongue, or eyelids; dizziness; abdominal pain; or nausea or vomiting in conjunction with hives, seek assist immediately.

Duration of Hives

“A hive lesion doesn’t generally final much longer than 24 hours, whereas things love bug bites, which are easily confused with hives, can final several days,” Friedman says.

That means you might wake up with a hive one morning — and that one specific hive may be completely gone by the next morning, Friedman says. “And they often appear without any warning.”

Hives also move around, and they don’t necessarily care what body part they inhabit. Even your scalp, soles of your feet, and palms of your hands can get hives. “If you see one moving a lot, that signals a hive,” Friedman says.

RELATED: How to Identify Common Bug Bites and Stings

Acute hives final less than six weeks, while chronic hives final more than six weeks. That doesn’t mean you’re covered in hives every day during these time periods, but it does mean that during these time frames, the hives come and go either erratically or sometimes on a more consistent basis, says Anthony M.

What does h/o drug allergy mean

Rossi, MD, an assistant attending dermatologist at Memorial Sloan Kettering Cancer Middle in New York City.

Fortunately, although they might itch a lot, hives don’t leave any marks on the skin once they vanish, regardless of whether you’ve treated them or not.

Hives are neither contagious nor, in most cases, dangerous. There are, however, a few exceptions that should immediate emergency care.

The first is a condition called angioedema, which involves swelling of the tissue beneath the skin. That can lead to swelling in the tongue, lips, throat, hands, feet, and even the inside of the abdomen.

As a result, people could own stomach cramps or worse, difficulty breathing. People with hives can own angioedema, but note that “just because you own hives doesn’t mean you’ll get angioedema,” Dr. Rossi says.

When hives are accompanied by swelling and breathing becomes hard, seek emergency care correct away.

Hives may also be the result of a serious allergic reaction called anaphylaxis, Rossi says. If you experience difficulty breathing; swelling of your lips, tongue, or eyelids; dizziness; abdominal pain; or nausea or vomiting in conjunction with hives, seek assist immediately.

PEDIATRIC DENTISTRY
APPROVED ABBREVIATIONS

ABCDEFGHIJKLMNOPQRSTUVWXYZ

a before
ac before meals
ACC Ambulatory Care Center
ACNC Ambulatory Care Network Center
ad lib as desired
adm. admission; admit
adol. adolescent
A.E.D. antiepileptic drugs
Amal. amalgam
AI aortic insufficiency
ANC absolute neutrophil count
Ant. anterior
AP anteroposterior
APF acidulated phosphate fluoride
appt. appointment
APXR anterior posterior radiograph
AROM active range of motion
ASAP as soon as possible
ASD atrial septal defect
ASHD arteriosclerotic heart disease
AU both ears
AVM arteriovenoses malformation
AV Shunt arteriovenous shunt
AV node atrioventricular node
bact. bacteria
bid twice daily
bimax bimaxillary protrusion
blo.

cult.

blood culture
BM bowel movement
BMR bosel metabolic rate
BP blood pressure
B/L Band and Loop
BT bleeding time
Bu buccal tissue surface (not acceptable as tooth surface)
BUN blood urea nitrogen
BWXR bite-wing radiograph
bx biopsy
Bx behavior
Behavior Class/Frankel
Bx1 very uncooperative — unable to treat
Bx2 somewhat uncooperative — treated with grand difficulty
Bx3 somewhat cooperative — treated with some difficulty
Bx4 very cooperative — treated without difficulty
c with
ca calcium
CaOH calcium hydroxide
cap. capsule
CAT computerized axial tomography
Cath. catheter
CAT Scan computerized axial tomography
CBC complete blood count
CC chief complaint
cc cubic centimeter
CDE complete dental/oral evaluation
ceph. cephalometric radiograph
CHD congenital heart disease
CHF congestive heart failure
CHO carbohydrate
chol. cholesterol
cl chloride
c/o complains of
CO2 carbon dioxide
consult consultation
cont. continued
cm centimeter
CL cleft lip
CLPL cleft lip and palate
CPAP continuous positive airway pressure
CPL cleft palate
C/N cannot
CNS central nervous system
CP cerebral palsy
CPR Cardiopulmonary Resuscitation
Cr crown
CSF cerebrospinal fluid
CTSP called to see patient
ctx chemotherapy
CVA cerebrovascular accident
CXR chest x-ray
D distal tooth surface
D/C discharge/discontinue
D&C dilation and curettage
DD developmental disability
Derm. dermatology
DH dental hygienist
DIC disseminated intravascular coagulation
disch. discharge
Div. division
D/N, DN does not
DOH Department of Health
DPT diphtheria, pertussis, tetanies
DT diphtheria, tetanus
DVR Department of Vocational Rehabilitation
DVT deep vein thrombosis
Dx diagnosis
ECG/EKG electrocardiogram
EEG electroencephalogram
emerg. emergency
EMG electromyogram
Endo. endodontics
EENT ear, eyes, nose and throat
ENT ear, nose and throat
eos. eosinophils
EPT electric pulp test
ESR erythrocyte sedemention rate
ETCO2 end title carbon dioxide (blood level)
ETOH ethanol
exam examination
exc. excision
ext. extraction
Extremities
LUE left upper extremity
LLE left lower extremity
RUE right upper extremity
RLE right lower extremity
F facial tooth surface
FBS fasting blood sugar
FC formocresol
Fe iron
FFP fresh frozen plasma
FH family history
Fl, F2 fluoride, topical application
F/U follow-up
FUO fever of unknown origin
Fx fracture
GA general anesthesia
GI gastrointestinal
GIC glass ionomer cement
GIR glass ionomer resin
gm gram
gr grain
GT gastrostomy tube
gtt(s) drop(s)
GU genitourinary
GY/GYN. gynecology; gynecologic
h hour
Hct hematocrit
Hep A hepatitis A
Hep B hepatitis B
Hep non-A non-B hepatitis non-A non-B
Hep C hepatitis C
HBSAg. Hepatitis B surface antigen
HBV Hepatitis B virus
hgb hemoglobin
HIV human immune deficiency virus
H&N head and neck
H/O history of
H&P history and physical
HPI history of present illness
hs bedtime/hour of sleep
HR heart rate
hr. hour
ht. height
HHx health history
Hx history
I incisal tooth surface
IA intraarterial
ICU intensive care unit
I&D incision and drainage
IDDM insulin dependent diabetes mollitus
IM intramuscular
Imp. impression
IQ intelligence quotient
IPT indirect pulp therapy
IRM intermediate restorative material
IU intraventricular hemorrhage
IV intravenous
IVP intravenous pyelogram
IVPB intravenous piggyback
JVD jugular venus distension
JVP jugular venus pressure
K potassium
kg kilogram
KJ knee jerk
KUB kidneys, ureter, bladder
K-wire Kirschner wire
l liter(s)
L lingual tooth surface
left
LA local anesthesia
lab. laboratory
lat. lateral
lb. pound(s)
LE lower extremity
LFT liver function test
lig. ligator, ligature
LL lower left
LLA lower lingual arch
LLE lower left extremity
LLQ lower left quadrant
LMP last minute period
LOM lose of motion
LR lower right
LRE lower correct extremity
LRQ lower correct quadrant
LUE left upper extremity
LUQ left upper quadrant (abdomen)
Lungs:
LUL left upper lobe
LLL left lower lobe
RUL right upper lobe
RML right middle lobe
RLL right lower lobe
lymphs. lymphocytes
M mesial tooth surface
M&T myringotomy and tubes
malocc. malocclusion
max. maxillary, maxilla
mand. mandibular, mandible
MBD minimal brain dysfunction
mcg microgram
med. medicine
mEq milliequivalent (per liter)
MG magnesium
mg milligram(s)
MI myocardial infarction
min. minute(s)
ml milliliter
mm millimeter
MMR mumps, measles, rubella
mod. moderate
mono. monocyte
mos months
MPD myofacial pain dysfunction
MR mentally retarded
MRA magnetic resonance angiography
MRE manual resistive exercise
MRI magnetic resonance imaging
MVA motor vehicle accident
Na sodium
NA not applicable
NAC no anesthetic complications
NAD no acute distress
NC non contributory
Neb. nebulizer
Neuro neurological
NCTRDC no contraindications to routine dental care
NG nasogastric
NGT nasogastric tube
nil nothing
NKA no known allergies
NKDA no known drug allergies
neg. negative
NL normal
N2O nitrous oxide
NPN non-protein nitrogen
NPO nothing by mouth
noct. nocternal, night
NS normal saline
NSR normal sinus rythmn
NV next visit
NWB non weight bearing
O occlusal tooth surface
O2 oxygen
O2 sat oxygen saturation
obs. observation
OH oral hygiene
OHI oral hygiene instruction
OHIG oral hygiene instruction given
OHM Oral Health Maintenance
OHM F/U oral health maintenance follow-up
OM otitis media
OMFS oral maxillofacial surgery
OPC out-patient clinic
OPD out-patient department
OP operation
O R operating room
Ortho. orthopedic
Orthodont.

orthodontic
OT occupational therapy
OXR occlusal radiograph
p after
P phosphorus
PAXR periapical radiograph
panXR panoramic radiograph
path. pathology
pc after meals
PDA patent ductus arteriosus
PE physical exam
Ped pediatric
Ped Dent pediatric dentistry
PEEP positive finish expiratory pressure
percuss percussion
perm. permanent
PERRLA pupils equal, circular, reactive to light and accommodation
PFT pulmonary function test
PH past history
pH hydrogen ion concentration
PI performance improvement
PICPF Proper infection control procedures followed
PIP peak inspiratory pressure
p.o. by mouth
pos positive
post. posterior
post.

op.

postoperative
POx pulse oximeter
pre.

What does h/o drug allergy mean

op.

preoperative
PNP pediatric nurse practitioner
POI postoperative instructions
PP pulpotomy
PPD purified protein derivative
PPT pulpectomy
pr per rectum
Prep. prepare for
pri. primary (tooth)
prn as necessary
prophy. dental prophylaxis
Pt. patient
PT physical therapy
PTA prior to admission
PTT partial thromboplastin time
PVC premature ventricular beat
Px prognosis
q every
Q quadrant
QA quality assurance
qd every day
qh every hour
qhs. at hour of sleep
q2h, q4h, etc. every 2 hours, every 4 hours, etc.
QI quality improvement
qid four times daily
QM quality management
qns quantity not sufficient
qod every other day
qs sufficient quantity
quant. quantity
R right
RA rheumatoid arthritis
RBC red blood count
r.b.c. red blood cells
Rad./XR radiograph(s) / x-rays
RCT root canal treatment
RC resin (strip) crown
RD rubber dam
RDS respiratory distress syndrome
resp. respiratory
Rest. restoration(s), dental
Rh Rhesus blood factor
RHD rheumatic heart disease
RL ringer’s lactate
RLL right lower lobe (lung)
RML right middle lobe (lung)
RO rule out
RR respiratory rate
RRt retained root
RSNR resin restoration
RT radiation therapy
RTI respiratory tract infection
RUL right upper lobe (lung)
RV residual volume
R prescription/recommendations for treatment ortherapy
s without
SA skeletal age
SAO2 oxygen saturation
SCI spinal cord injury
SDH subdural hematoma
Seal. sealant
sec second(s)
sed sedation
sed rate sedimentation rate
SH social history
sib sibling
SL sublingual
SM submucosal
SOAP subjective, objective, assessment, plan
sol. solution
S/P status post
spec. specimen
SQ subcutaneous
ss one half
SSC stainless steel crown
ST speech therapy
staph.

staphylococcus
Stat. immediately and once only
Strep. streptococcus
SURG surgery
Sx symptoms, signs
T, temp temperature
T&A tonsillectomy and adenoidectomy
tab. tablet
TB tuberculosis
TBI tooth brushing instruction
Tbsp. tablespoon
TFA topical fluoride application
TIA transient ischemic attack
tid three times daily
TM tympanic membrane
TMD temporomandibular dysfunction or disorder
TMJ temporomandibular joint
TO telephone order
TPR temperature, pulse & respirations
trach. tracheostomy
trx traction
tsp. teaspoon
TT thrombin time
Tx treatment
U upper
UA urinalysis
UBW upper body weight
UE upper extremity
ug microgram
UGI upper gastrointestinal
uk unknown
ULQ upper left quadrant
UL upper left
ULE upper left extremity
UR upper right
URE upper correct extremity
URQ upper correct quadrant
URI upper respiratory infection
Urol. urology
UTI urinary tract infection
USOH usual state of health
v very
VA shunt ventriculoatrial shunt
VC vital capacity
vent. ventilator
vent dep ventilator dependent
vit vitamin
VO verbal order
VP shunt ventriculoperitoneal shunt
VPB ventricular premature beat
VQ verbal cues
VS vital signs
VSD ventriculoseptal defect
VSS vital signs stable
WB whole blood
WBC white blood cell count
wbc white blood cells
W/C wheel chair
WD WN well developed, well nourished
wks weeks
WNL within normal limits
wt weight
X-bite cross bite
XR radiograph/x-ray
XRT radiation therapy

ZOE zinc oxide and eugenol

Note: Abbreviations are not to be used for names of systemic medications.

* Corresponding authors

a School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
E-mail:[email protected]

b NSF/NASA Middle for Chemical Evolution, USA

c Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA

d School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA

Source: Dr P Marazzi / Science Photo Library

All forms of natural and semisynthetic penicillins, or drugs with similar structures can cause allergy.

In the image, penicllin allergy rash in forearm

In this article you will learn:

  1. The drugs to avoid in patients with penicillin allergy
  2. The incidence of true penicillin allergy
  3. How to manage patients who experience a severe allergic reaction to an antibiotic

All forms of natural and semisynthetic penicillins, or drugs with a similar structure such as cephalosporins or carbapenems, can cause allergy. These drugs, which own a beta-lactam ring, are recognised as one of the most frequent causes of immediate and non-immediate drug reactions[1],[2],[3].

Adverse reactions to penicillin own been reported in 0.2% per course of treatment in a large unselected cohort[4], and between 3.3–5% in a large drug surveillance programme[5],[6].

However, a significant number of patients labelled as ‘penicillin allergic’ are not truly allergic to the drug[7]. As a result, these antibiotics can be withheld unnecessarily, which may subsequently affect their clinical outcomes, increase healthcare costs and contribute to the development of drug resistant bacteria.

The prevalence of penicillin hypersensitivity in the general population is unknown as no prospective studies evaluating sensitisation rates during treatment own been undertaken to date[8].

However, from data extracted from the electronic health medical records of patients who had at least one outpatient visit, the prevalence of ‘allergy’ in the general population appears to be around 9% for penicillins and 1.3% for cephalosporins[9].

The incidence of true penicillin allergy (a type I reaction which is immunoglobulin E [IgE] mediated) is <0.05% of the general population[10]. True penicillin allergy can be fatal[11],with a risk of anaphylaxis estimated in around 0.002% of treated patients[12]. A UK study of drug-induced fatal anaphylaxis between 1992 and 1997 reported 12 deaths due to antibiotics[13],[14].

Up to 20% of drug-related anaphylaxis deaths in Europe and up to 75% of deaths for every drug-related anaphylaxis in the USA are caused by penicillin[15],[16],[17].


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