Sunday , July 25 2021

You probably do not have a penicillin allergy



You probably do not have a penicillin allergy

Doctors Derek Chu, left, and David McCullagh of McMaster University. Credit: Tina Depko / McMaster University

You may think you have an allergy to penicillin, but you probably do not.

Nine out of 10 people who believe that they are allergic to the antibiotic either are not allergic or have only some intolerance, and eight of 10 people who have had an allergic reaction to penicillin 10 or more years ago will now be fine.

Two McMaster University physicians have five facts about penicillin allergy published today in Canadian Medical Association Journal (CMAJ). Derek Chu is a fellow in clinical immunology and allergy and David McCullagh is a fellow in infectious disease in the Department of Medicine.

They say the five things to know about a penicillin allergy are:

  • Penicillin allergy is commonly reported, but nine times out of 10, a patient can tolerate penicillin. About 10 percent of people report a penicillin allergy but 90 percent to 95 percent are not really allergic. Reasons for this include mislabelling intolerances as allergies and waning of allergy over time.
  • Penicillin allergies are lost over time, with 50 percent of people over five years, and 80 percent over 10 years of their allergy loss. Those who have had reactions more than 10 years ago are unlikely to still be allergic and should be tested before given penicillin . If there is a strong indication for antibiotics, an allergic physician should be consulted about the treatment.
  • A penicillin allergy label is bad for patients and the health care system.People tagged with penicillin allergy are offered more costly and less effective second-line and broad-spectrum antibiotics which have a significantly increased risk of infections such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C. diff).
  • Patients who suspect penicillin allergy can be identified to determine if they should be seen by a specialist. A side effect of penicillin such as nausea should not be noted as an allergy. As well, people without a personal history of a penicillin allergy or who have tolerated penicillin in the past, do not need to avoid penicillin. Severe allergic drug reactions due to widespread skin blistering, organ failure, and / or joint swelling are rare and these patients should strictly avoid penicillin until specialist evaluation. True immediate allergic reactions cause rapid-onset hives, lip and face swelling, and anaphylaxis. Patients with these types of reactions, who are unsure whether this type of event has occurred or not, should be evaluated by an allergy specialist.
  • Allergy referral and testing is underused but is safe, accurate, fast and cost-effective. Allergy testing over one to two hours using a combination of skin and challenge testing by trained staff has been shown to be safe and effective for children and adults close to 100 percent of the time. Patients with a possible penicillin allergy should talk to their doctor about whether or not they need penicillin allergy testing.

You might be allergic to penicillin-then again, you might not


More information:
                                                    David J. McCullagh et al. Penicillin allergy, Canadian Medical Association Journal (2019). DOI: 10.1503 / cmaj.181117

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                                                                                                            McMaster University

Citation:
                                                 You probably do not have a penicillin allergy (2019, February 25)
                                                 retrieved 25 February 2019
                                                 from https://medicalxpress.com/news/2019-02-dont-penicillin-allergy.html

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