The Allegory of My Penicillin Allergy

By Nicola Welch - AMWA Member

It was on a family trip to Mildura in north-west Victoria as a young child that I was first given penicillin. While I don't remember why, nor do I remember the rash I developed, it was then I was first introduced to my penicillin allergy - a seemingly innocuous friend that nonetheless threatened its pernicious intentions should it be taken for granted. I remember the small disc I wore around my neck to alert anyone of the foreboding danger that lay ahead should I be given the drug. When I was a teenager I had a RAST test (radioallergosorbent test) to check my blood for specific lgE antibodies and determine if I was in fact allergic to penicillin. It was negative! My allergy had resolved - well no, actually, this was not a sure thing, I was told. While the RAST test quantifying IgE gives negative results in more than 95% of people who do not have a true penicillin allergy, it gives positive results in only 20% of people with a true penicillin allergy; and less than 50% of those with positive blood tests have a true penicillin allergy. [1] Thus, armed with confusion and the suboptimal diagnostic accuracy of a negative penicillin test, I continued to list penicillin as an allergy. 

As life unfolded I managed well despite my inability to take penicillin, although my seemingly innocuous friend would often reappear offering unwanted advice and confusing direction. When I had my wisdom teeth removed and developed an adverse reaction after surgery, it was suggested that perhaps I was allergic to the pain medication I was given - being that I was ‘prone to allergy.’ When I had my daughter and did not initially respond as expected to the drugs used in the spinal block, it was suggested that perhaps my ‘other allergy’ could somehow help to explain why. And then, after Iiving abroad for 14 years, I returned home to Australia to a particularly brutal winter and ended up with an ear infection. I had been successfully cured of ear infections before (in spite of my penicillin allergy) but this time I was breastfeeding, and this, coupled with my allergy, meant that my antibiotic options were limited. I was prescribed an antibiotic but was told that it was not ideal or specifically indicated for ear infections, but given my situation, it would be the safest option; and hopefully effective. Ten days later my ear infection remained unresolved and I felt ill most of the time - a side effect of the antibiotic and perhaps sensitivity to it because of my ‘allergic nature’. Nonetheless, my doctor suggested another 10-day course - reluctantly I took it. Eventually my ear infection resolved but I wonder if the antibiotic actually helped. 

My collective experiences crystallized my resolve to obtain a conclusive diagnostic answer. I was referred to the Austin Hospital Antibiotic Allergy Clinic, “a novel service that provides comprehensive clinical assessment, skin testing and oral challenge to patients with a history of antibiotic allergy”. [2] The waiting list is long unless you are a ‘high priority’. Did I qualify as a high priority? My situation was not dire. There was no imminent threat - but rather a long term lingering impact on my quality of life. I was lucky and secured an appointment within a relatively short time frame. Comprehensive clinical assessment; skin testing; oral challenge - and within a few hours I had my answer - I was unequivocally not allergic to penicillin - an unexpected weight was lifted. My false friend was gone. This made me wonder how common my experience was and what, if any effect, a misdiagnosed penicillin allergy may have beyond my own experience. I was amazed by what I found after dipping my toe in the research pool. 

I found my first answer from the Austin Hospital Antibiotic Allergy Clinic itself. Their website states: “Whilst 10-20% of the population are “labelled” as penicillin allergic, only 1-2% are positive on formal testing.” [2] And the impact? Far reaching! Research shows that patient-reported penicillin allergies change antibiotic management and may result in the use of suboptimal or broader spectrum drugs. [3-7] Having a penicillin allergy label has been associated with an increased risk from other infections. [8] The increased use of broad-spectrum drugs in hospitalised patients with penicillin allergies also contributes to the growing global problem of antimicrobial resistance. [3, 5, 9, 10] Antibiotic allergy labels are correlated with hospital readmission rates, [6] increases in length of hospital stay, [11] surgical site infections [12] and admissions to intensive care units. [13] Similarly in general practice, penicillin allergy labels are associated with an increased risk of treatment failure, resistance generation, and increased death. [14] While I did not find any evidence-based research specifically reporting on the effect of misdiagnosed penicillin allergy on quality of life, I venture to think it is significant, given my experience.

And so, as I bid farewell to my penicillin allergy after many decades, I am changed by my profound experience and moved to share my story so others like me may learn from my allegory and not be misguided by the perceived nature of their situation and the broader implications but rather take an empowered step toward a future of improved quality of life, better patient outcomes and superior healthcare options both individually and for the community.


  1. Sousa-Pinto B, et al. J Allergy Clin Immunol. 2021 147(1):296-308.
  2. Austin Hospital Antibiotic Allergy Clinic.
  3. Sousa-Pinto B, et al. Ann Allergy Asthma Immunol 2018; 120:190-194.e2.
  4. Sacco KA, et al. Allergy 2017;72:1288-96.
  5. Sigona NS, Steele JM, Miller CD. J Am Pharm Assoc (2003) 2016; 56:665-9.
  6. MacFadden DR, et al. Clin Infect Dis 2016; 63:904-10.
  7. Huang KG, et al. Clin Infect Dis 2018; 67:27-33.
  8. Macy E, Contreras R. J Allergy Clin Immunol 2014;133:790-6.
  9. Blumenthal KG, et al. J All Clin Immunol Pract 2017;5:616-25 e7.
  10. Chen JR, et al. J Allergy Clin Immunol Pract 2017;5:686-93
  11. Knezevic B, et al. Intern Med J 2016;46:1276-83.
  12. Blumenthal KG, et al. Clin Infect Dis 2018;66:329-36.
  13. Charneski L, Deshpande G, Smith SW. Pharmacotherapy 2011;31:742-7.
  14. West RM, et al. J Antimicrob Chemother 2019;74:2075-82.

Nicola Welch, PhD, CMPP is Managing Director and Senior Medical Writer at Whipbird Communications, a medical communications company based in Melbourne, Australia that provides comprehensive medical writing services, tailored tools to innovate, manage, and streamline processes and a medical writing education platform for clients in the academic, medical, biomedical, scientific, healthcare, engineering, biotechnology and pharmaceutical industries. Visit Whipbird Communications to learn more.

Member Spotlight - Michael Molloy-Bland

Michael gained his PhD at Otago University and then secured a postdoctoral research position at the University of Oxford. He is currently working as Scientific Director in the Melbourne office of Oxford PharmaGenesis, working remotely from New Zealand. His role mainly involves overseeing strategy and content development for scientific publications across several client accounts.
He shares more about his journey, and some very wise insights and words of advice, on our Member Spotlight page.

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