Antibiotics Archives - Rxplanation.com

Penicillin allergy is reported by up to 10% of the general population, making it the most commonly reported drug allergy. However, as many as 95% of these people are not truly allergic to penicillin; meaning that the true rate of penicillin allergy is closer to 0.5% to 1%. Let's take a closer look at penicillin allergy, and why it's important to remove it from your medical record (i.e. "de-label") if you're not truly allergic. What is an allergy? One reason the term allergy gets thrown around inappropriately so much is because many people are not aware of the definition of a "true allergy". There are many types of adverse reactions that can happen when we take a drug. While allergies are one of these categories, they are not the only type of reaction that can occur. I've created a simplified/adapted version of the oft-cited "Coombs and Gell Classification of Hypersensitivity Reactions" table in order to better illustrate the differences between types of reactions: Type of reactionTimeframeReactioncharacteristicsSide effectsAnytimeThese are oftenpredictable(e.g. headache, upset stomach)"True" allergyImmediate(usually withina few hours, butup to 72 hours) Hives, itchiness, swelling of the mouthor face, anaphylaxis, difficulty breathing, etc.Minor delayedreactionsDelayed(usually morethan 72 hours)Generalized red rash(usually symmetricaland not that itchy)Severedelayedreactions Delayed(usually morethan 72 hours) These rare reactionsare more severe, some are even life-threatening.(E.g. serum sickness,Stevens-Johnson syndrome,DRESS syndrome)Adapted from the Coombs and Gell Classification of Hypersensitivity Reactions As you can see in the table above, a true allergy is an immediate reaction. It is caused by the immune system falsely recognizing and attacking a specific substance. These tend to occur quite rapidly (usually in the first 24 hours), but sometimes can occur up to 72 hours after starting the medication. It's important to note that there can be some overlap between the various categories of reactions. This can often make it difficult for patients to know if they have an allergy (or something else). Some physicians even struggle with telling the difference between an allergy or another type of reaction. How often is penicillin allergy reported? As I said in the introduction, penicillin allergy is the most commonly reported drug allergy. The rate of how often it's reported will actually vary by the population being surveyed. In the general population, up to 10% of people will report a penicillin allergyIn hospitalized patients, the rate is even higher: reaching up to 15 to 20% of people reporting a penicillin allergy. Why are so many people saying they're allergic to penicillin? The first problem is that years ago healthcare professionals didn't put much thought into allergy labels, and tended to err on the side of caution. They (falsely) assumed that being extra cautious wouldn't hurt....more on that later. There are also many misconceptions surrounding "allergies": Falsely assuming that side effects (e.g. headache, diarrhea, upset stomach) are drug allergiesMisplaced concern that penicillin allergy could be hereditary/inherited (penicillin allergy is not hereditary; so if one of your parents is allergic to penicillin, this is not a reason to assume you would be allergic)Because so many people report a penicillin allergy, most people assume it's more common than it really is Can you "lose" or "grow out of" a penicillin allergy? In those people who truly have a confirmed penicillin allergy, it's possible for them to "lose" the allergy over time. Research has shown us that after 5 years approximately 50% of people will lose their allergy, and after 10 years this goes up to 80%. Clearly, this is not 100%, so I would not advocate for people with a true allergy to assume they no longer have one. But, the knowledge that penicillin allergy is not "'til death do us part" can make it easier to accept for people. I've had a few instances at work where someone is definitively proven not to be allergic to penicillin, yet they refuse to accept this. It seems like some people associate their allergy as a part of their personality, and almost feel like we are taking away their passport when we de-label their penicillin allergy. So, understanding that even a true allergy isn't always for life can make it easier to accept if ever it is disproven later on. What's the big deal if I have a false penicillin allergy label? This may come as a surprise to some people, but there are many reasons why you wouldn't want to have a falsely labeled penicillin allergy in your chart. The following have all been shown to be potential consequences of having a penicillin allergy label in your medical record: Reduced use of preferred antibiotics for many common infections (e.g. strep throat)Increased risk of C. difficile infection (alternative antibiotics have a higher risk of C. difficile infection)**See this other post for more information on why antibiotics cause C. difficile.Increased risk of developing antibiotic resistant bacteria (such as MRSA and VRE)**See this other post for more information on antibiotic resistanceMore drug side effects (alternative antibiotic options tend to have more side effects)More treatment failures (alternative antibiotic options often don't work as well)More post-op infections after surgeries (alternative antibiotic options often don't work as well)Longer hospital stayMore likely to need to be re-admitted to the hospitalMore likely to require intensive care during a hospitalizationMore likely to die while in hospital How I assume some of you looked when reading that list Sadly, having a penicillin allergy label in your medical record can have some real consequences. This is why it's important to ensure that you are properly evaluated to make sure that you truly have an allergy (and that it needs to be listed in your medical record). What can I do if I want my penicillin allergy to be evaluated? There are many different ways to evaluate a penicillin allergy. Sometimes, we can de-label the allergy as easily as just doing a detailed questionnaire. Other times, we can do a "test dose" where we give a dose of amoxicillin (a type of penicillin) to someone that we questioned and assume isn't allergic. This test dose is just to be extra certain. In the instances where we just can't rule out a true allergy, there is a type of skin test that can be done to test if you have an allergy to penicillin. These are often done by allergists (specialists), but are now being used more and more by non-specialists. There are now even some hospital pharmacists who have done them. If you aren't sure if you're truly allergic to penicillin, don't hesitate to contact one of your healthcare providers (doctor, nurse practitioner, pharmacist). The Bottom Line Despite being one of the most commonly declared drug allergies, penicillin allergies are not as common as many people are led to believe. Up to 95% of people who declare a penicillin allergy are not truly allergic. Simply having a penicillin allergy label in your medical record can put you at increased risk for many bad outcomes. This is why it's absolutely essential that vague, unknown, or doubtful allergies be properly investigated. References NB Provincial Health Authorities Anti-Infective Stewardship Committee. Management of Penicillin and Beta-Lactam Allergy. September 2017Macy E and Ngor E. Clinic Rev Allerg Immunol 2014; 47:46-55Blondel-Hill and Fryters. Bugs and DrugsLagacé-Wiens P. and Rubinstein E. Expert Opin. Drug Saf. 2012(11):381-99Solensky R. J Allergy Clin Immunol. 2012; 130(6):1442-1442.e5.American Academy of Allergy Asthma and Immunology. Penicillin Allergy FAQ. September 2020Macy, E. & Contreras, R. (2014). J Allergy Clin Immunol, 133(3): 790-796.Charneski, L., Deshpande, G. & Smith, S.W. (2011). Pharmacotherapy, 31(8): 742-747.MacFadden DR. Clin Infect Dis 2016;63:904.Jeffres MN. J Allergy Clin Immunol 2016;137:1148Blumenthal KG. PLoS One 2016;11:e0159406.Conway EL. Clin Ther 2017;39:2276.Desai SH. Perm J 2017;21:16.Blumenthal KG. J Gen Intern Med 2019; doi: 10.1007/s11606-019-04991-y.Blumenthal KG. Clin Infect Dis 2018;66:329.Macy E. J Allergy Clin Immunol 2017;5:705.Du Plessis T. J Antimicrob Chemother 2019;74:1438.Trubiano JA. Antimicrob Resist Infect Control 2015;4:23.