Penicillin Allergy

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* It is important to document exactly what symptoms occurred before deciding if a patient is truly penicillin allergic. Check with Patient / Relatives / GP / Community Pharmacy to clarify the nature of allergic reaction:

  • Many patients are misdiagnosed as being Penicillin allergic
  • An incorrect diagnosis of penicillin allergy leads to unnecessary avoidance of this relatively non-toxic class of drugs, exposes the patient to potentially more toxic drugs, increases health care costs and contributes to the development of antibiotic resistance.
  • Patients are often labelled as having a hypersensitivity reaction when in fact a patient may be experiencing a side effect of penicillin, such as gastrointestinal upset (e.g. nausea, diarrhoea) or headache.
  • Other concomitant medicines can also be responsible for triggering a hypersensitivity reaction. Therefore, it is important to consider the timeframe over which the hypersensivity reaction has developed relative to the initiation of different medications.
  • Patients who have previously presented with a less severe penicillin allergy (e.g. rash - NB: i.e. Non-severe reaction e.g. mild-moderate rash not on the EM/SJS/TEN spectrum of rash and not requiring hospitalisation ) may be considered to be prescribed cephalosporins/carbapenems if the benefits outweigh the risks of cross reactivity. This is a clinical risk assessment. The potential for an allergic reaction should be monitored and resuscitation equipment available if required.
  • Patients who are documented as having experienced a severe reaction (e.g. anaphylaxis) from a penicillin should not be prescribed cephalosporins, carbapenems and other betalactam containing antibiotics where acceptable alternatives available. A risk-benefit assessment may be needed in certain circumstances. Discuss individual case with senior clinician and clinical microbiology team if needed.