Written by Dr. Roland Solensky, Corvallis Clinic

About one out of ten of us reports a history of penicillin allergy. That translates to over 30 million people in the United States. The first inclination is to think that this is no big deal, since we have many other classes of antibiotics to choose from. However, it turns out that patients who are labelled penicillin-allergic are more likely to receive “big gun” broad-spectrum antibiotics, or be treated with antibiotics that are less effective or not the best-suited for their infection. It is known that use of some of these antibiotics, such as quinolones and clindamycin, is tied to development of resistant bacterial infections and Clostridium difficile (C. diff) colitis. Research has shown that patients labeled penicillin allergic are more likely to be diagnosed with serious antibiotic resistant infections such as VRE (vancomycin resistant enterococci) and MRSA (methicillin resistant Staph aureus), as well as C. difficile colitis. Additionally, patients labeled penicillin allergic, on average, require longer hospital stays and have higher medical costs compared to patients who do not have a history of penicillin allergy.  

Fortunately, the most common types of penicillin allergy can be accurately diagnosed with penicillin skin testing, which is typically performed by allergists. Penicilin skin testing takes about ½ an hour to perform, and is similar to testing for environmental allergies (such as pollen or dust mites) or food allergies. When patients with a history of penicillin allergy undergo formal evaluation with penicillin skin testing, less than 10% are confirmed to be allergic. There are probably several reasons for this. First, penicillin allergy is known to wane and resolve over time in many (but not all) patients. Secondly, some patients experienced side effects such as stomach upset from penicillins, rather than a true allergic reaction, but were mislabeled as allergic. Thirdly, infections themselves may sometimes cause symptoms such as hives, but if a patients is also taking an antibiotic such as penicillin, it is impossible to distinguish the cause.

The CDC and others are undertaking educational campaigns to raise awareness regarding penicillin allergy, the poor outcomes associated with being labeled penicillin allergic, and the potential of penicillin skin testing removing the label of penicillin allergy. The bottom line is that penicillin allergy is a public health problem, and the vast majority of patients are unnecessarily labeled as penicillin allergic. To learn more about how to identify true penicillin allergies, please download this fact sheet from the Centers for Disease Control.

Dr. Roland Solensky, an allergist and immunologist, is an internationally-recognized expert in drug allergy. He developed an interest in drug allergy during his allergy/immunology fellowship at UT Southwestern in Dallas. He has been in clinical practice at The Corvallis Clinic for fourteen years. He has published drug allergy articles in journals and book chapters. He has also been involved in various Academy of Allergy, Asthma and Immunology (AAAAI) leadership positions, and was the editor of “Drug Allergy: An Update Practice Parameter,” which is a guideline for physicians on how to approach patients with drug allergy.