on Antibiotic Choice for Patients with Penicillin Hypersensitivity
phrase ‘allergic to penicillin’ is commonly seen in medical notes and on
medicine charts. The diagnosis of ‘penicillin allergy’ is often simply
accepted without obtaining a detailed history of the reaction. It has been
reported that a significant percentage of patients labelled as ‘penicillin
allergic’ are not truly allergic to the drug. As a result, penicillins are
unnecessarily withheld from these patients, which may subsequently affect their
What is the True Incidence of ‘Penicillin Allergy’?
General hypersensitivity reactions (e.g. rashes) to penicillin occur in between 1 and 10% of exposed patients but true anaphylactic reactions (which can be fatal) occur in less than 0.05% of treated patients. Please note that patients who have a vague history of symptoms or gastro-intestinal intolerance are probably not truly allergic to penicillins.
Who is at risk?
Patients with a history of atopic allergy (e.g. asthma, eczema, hay fever) are more likely to be allergic to penicillins.
Who should not be prescribed or administered penicillins?
Individuals with a history of Type I allergy clinically recognisable by features of urticaria, laryngeal oedema, bronchospasm, hypotension or local swelling within 72 hours of administration, or development of a pruritic rash (even after 72 hours) should NOT receive a penicillin.
Are there situations where cephalosporins or other beta-lactam antibiotics can be prescribed for patients with penicillin hypersensitivity?
Clinical studies suggest that the incidence of cross-reactivity to cephalosporins in penicillin-allergic patients is around 10% but this is thought to be an overestimate. The true incidence of cross-sensitivity is uncertain. Second and third generation cephalosporins are unlikely to be associated with cross reactivity as they have different side chains to penicillin.
Patients with no evidence of Type I allergy to penicillin may be treated with any cephalosporin or beta lactam antibiotic for infections of any severity.
with symptoms suggestive of a Type I allergy should avoid cephalosporins and other beta-lactam antibiotics for mild
or moderate infections when a suitable alternative exists. In life
threatening infections, when use of a non-cephalosporin antibiotic would
be sub-optimal, consider giving, under observation, a second or third generation cephalosporin (e.g. cefuroxime,
ceftriaxone, ceftazidime). If
necessary seek advice from ID or Microbiology.
about other types of antibiotics?
Tetracyclines (e.g. doxycycline), quinolones (e.g. ciprofloxacin), macrolides (e.g. clarithromycin), aminoglycosides (e.g. gentamicin) and glycopeptides (e.g. vancomycin) are all unrelated to penicillins and are safe to use in the penicillin allergic patient.
Always identify and document the nature of the reported allergy and drug name on the medicine chart and in the medical notes. The prescriber has the primary responsibility for ensuring that the allergy/sensitivity details are completed on all relevant medicine charts and medical notes.
What should be prescribed for truly penicillin allergic patients?
|Urinary Tract Infections|
|Female Lower UTI||Trimethoprim or nitrofurantoin|
|Female Upper UTI||Co-trimoxazole + gentamicin|
|Male UTI||Trimethoprim or ciprofloxacin|
Upper Respiratory Tract Infections
|Tonsillitis||Erythromycin or clarithromycin|
|Otitis Media||Erythromycin or clarithromycin|
Lower Respiratory Tract Infections
|Community Acquired Pneumonia (non-severe)||Doxycycline|
|Community Acquired Pneumonia (severe)||IV Levofloxacin then oral doxycycline|
|Aspiration or Hospital Acquired Pneumonia (severe)||IV Vancomycin + metronidazole + gentamicin (and seek advice)|
|Aspiration or Hospital Acquired Pneumonia (non-severe)||Co-trimoxazole (+metronidazole if aspiration suspected)|
|Infective Exacerbation of COPD||Doxycycline|
Peritonitis/Biliary Tract/Intra-abdominal Infections
|Severe||IV Vancomycin + metronidazole + gentamicin (and seek advice)|
|Step down to oral||Cotrimoxazole|
|Cellulitis (see separate protocol)||Doxycycline|
|Animal bites||Metronidazole + doxycycline|
|Surgical Prophylaxis||See separate protocol|
here for information on which antibiotics should be avoided in penicillin
allergy, those that should be used with caution, and those that are safe.
Updated August 2008
Review August 2010
Pegler S, Healy B. BMJ 2007;335:991
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