Prescribers urged to double-check penicillin allergy is genuine

The importance of discussing penicillin allergies with patients has been highlighted after research finds that both the patient and prescriber are often unsure whether a recorded allergy is genuine.

A close up image of half red and half yellow capsules, representing the drug amoxicillin.
Penicillins are highly effective and inexpensive, and are the first-line treatment for many infections. | GETTY IMAGES

Penicillin allergy is the most commonly noted drug allergy in the UK, reported by about 1 in 15 people. However, it is estimated that fewer than 10% of those with the allergy listed in their medical records are truly allergic.

Incorrectly labelling patients as penicillin-allergic can have negative outcomes for the patient including longer hospital stays, an increased risk of both surgical-site infection and infection with antibiotic-resistant suberbugs such as MRSA, and death. It also means that patients may instead receive broad-spectrum antibiotics, which is likely to contribute to antibiotic resistance. 

Now, an interview study has suggested that primary care physicians and patients may be insufficiently aware of the potential harms associated with an incorrect record of penicillin allergy. 


Researchers interviewed 31 patients and 19 primary care doctors in North England. They found that most patients accepted the diagnosis of penicillin allergy without question, and had limited understanding of the symptoms of allergy versus side effects. 

Doctors said they often made the decision not to prescribe penicillin even if they doubted the recorded allergy, although some felt confident to challenge the allergy label and prescribe penicillin. One prescriber said: 'If a penicillin-based antibiotic is the best option, I sometimes have a conversation with the patients about whether they are happy to have a trial or not and the vast majority that I have done that to have taken the stuff and have been absolutely fine. You do it on a case-by-case basis depending on what you think is the most appropriate antibiotic for that patient and how you think that person will handle the situation if they start to show allergic symptoms again or not.' 

A small number of doctors had experience of challenging allergy records by referring patients for formal testing in secondary care but most were unsure about referral criteria and what the testing involved.

Most doctors did not initiate discussions with patients about the negative outcomes of having an incorrect record of penicillin allergy on their notes, saying that it wouldn't affect patients' day-to-day lives. 

The researchers concluded that discussions with patients about their penicillin allergy and the negative consequences of an incorrect record, with a particular focus on the difference between a side effect and an allergic reaction, might be beneficial.

Documenting allergies

NICE guidance recommends prescribers document any new suspected drug allergies in: 

  • the generic and brand name of the drug suspected to have caused the reaction, including the strength and formulation 
  • a description of the reaction 
  • the indication for the drug being taken 
  • the date and time of the reaction 
  • the number of doses taken or number of days on the drug before onset of the reaction
  • the route of administration. 

Prof Gillian Leng, deputy chief executive of NICE said: 'Lots of people think they are allergic to penicillin because it gave them a rash when they were a child, their mum or dad told them they were allergic and it has stayed in their notes for decades. That is a very different thing to having a true penicillin allergy, which can result in a life-threatening anaphylactic reaction.'

'If healthcare staff use NICE guidance to distinguish properly between the two, that could help stop the spread of both MRSA and antimicrobial resistance', she added. 

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