Penicillin Allergy?

By Haley Gandy, PharmD. Candidate 2021,
University of Kansas School of Pharmacy

October 28, 2020

Penicillin

Almost 15% of Americans report a penicillin allergy, yet 90% of these people can actually tolerate this antibiotic. [i] Antibiotic allergy labels (AAL) in general are on 25% of hospitalized patients, and 77% of these are from 10 years ago or more. This creates a limitation for prescribing the preferred antibiotic for the bacteria it’s being used to treat. [ii] Penicillin antibiotics are the most commonly used antibiotic in the US, and also make up a lot of the noted antibiotic allergies. [iii]

Knowing the Differences Between Reactions

It is worth discussing with your doctor what type of reaction you experienced, as well as the length of time that has passed since you had this reaction. They will have the expert knowledge to determine if you are a candidate to retry a penicillin. Reactions range from non-severe redness, to throat tightening, to very severe and serious skin reactions. Here is a helpful link to learn more about different reactions to medications as well as how to treat them: https://acaai.org/allergies/types/drug-allergies

If you have a history of antibiotic-related throat swelling, shortness of breath, hives, swelling, stomach upset, or headaches it is possible that your doctor can safely retest your penicillin allergy. It is important to know, if you have any of the following conditions that your doctor should not retest your allergy: severe liver or kidney disease, certain types of anemia, or a history of severe skin reactions. [iv]

What Does a Retest Consist of?

In order to retest your allergy, the doctor will first do a skin test with a penicillin topical treatment. This test will either confirm or reject the accuracy of the allergy. Around 95-99% of the time, the test shows that the patient does NOT have a true allergy, and that the next step can be taken to confirm this finding. If these results are negative, they will continue your test with a small amount of oral amoxicillin. [v]

What are Penicillin Alternatives?

When a patient has a penicillin allergy noted in their file, the prescriber is also unable to prescribe amoxicillin, which is a very common antibiotic with a wide range of uses. It is possible that the doctor could prescribe a drug with a slightly different structure such as a Keflex, but when an allergy is listed in the file, doctors don’t challenge the allergy since this medication is a cousin of penicillin. The prescriber then has to choose from less effective, and potentially more harmful antibiotics such as levofloxacin, ciprofloxacin, clindamycin, cefdinir, and others. [vi]

A recent study found that 16% of patients with a documented penicillin allergy were twice as likely to receive one of these antibiotics. This study also found that the alternative antibiotic of choice was clindamycin which increases the risk of developing a Clostridium difficile (C. diff) infection. Antibiotics such as these also contributed to antibiotic resistance because they mildly cover and expose themselves to a wide range of bacterias. [vii]

In 2014, there was campaign called Choosing Wisely Program through the American Board of Internal Medicine that highlighted the importance of not using these alternatives in patients with documented penicillin allergies unless they tested the accuracy of the allergy. Antibiotics that are related to penicillin but have different chemical makeup (such as Keflex mentioned above) can also safely be used in someone with a confirmed penicillin allergy. There is very little concern that antibiotics such as these will cause similar allergy symptoms. [viii]

What You Should Do

Rather than taking a potentially less-effective medication for an infection, talk to your provider about retesting your allergy, and possibly removing your penicillin allergy from your chart. Taking these allergy labels off your file could increase the quality of care you receive.

References:

[i] Joint Task Force on Practice P, American Academy of Allergy A, Immunology, American College of Allergy A, Immunology, Joint Council of Allergy A, et al. Drug allergy: an updated practice parameter. Ann Allergy Asthma Immunol. 2010;105:259-273.

[ii] Devchand M, Kirkpatrick CMJ, Stevenson W, Garrett K, Perera D, Khumra S, Urbancic K, Grayson ML, Trubiano JA. Evaluation of a pharmacist-led penicillin allergy de-labelling ward round: a novel antimicrobial stewardship intervention. J Antimicrob Chemother. 2019 Jun 1;74(6):1725-1730. doi: 10.1093/jac/dkz082. PMID: 30869124.

[iii] Macy E. Penicillin and beta-lactam allergy: epidemiology and diagnosis. Curr Allergy Asthma Rep. 2014;14(11):476. doi:10.1007/s11882-014-0476-y

[iv] Macy E, Ngor E. Recommendations for the management of beta-lactam intolerance. Clin Rev Allergy Immunol. 2014;47(1):46-55. doi:10.1007/s12016-013-8369-8

[v] Sacco KA, Bates A, Brigham TJ, Imam JS, Burton MC. Clinical outcomes following inpatient penicillin allergy testing: A systematic review and meta-analysis. Allergy. 2017;72(9):1288-1296. doi:10.1111/all.13168

[vi] Sacco KA, Bates A, Brigham TJ, Imam JS, Burton MC. Clinical outcomes following inpatient penicillin allergy testing: A systematic review and meta-analysis. Allergy. 2017;72(9):1288-1296. doi:10.1111/all.13168

[vii] Blumenthal KG, Kuper K, Schulz LT, et al. Association Between Penicillin Allergy Documentation and Antibiotic Use [published online ahead of print, 2020 Jun 29]. JAMA Intern Med. 2020;e202227. doi:10.1001/jamainternmed.2020.2227

[viii] Macy E, Ngor E. Recommendations for the management of beta-lactam intolerance. Clin Rev Allergy Immunol. 2014;47(1):46-55. doi:10.1007/s12016-013-8369-8

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