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2019-04-01 / OnCall

The Truth about Penicillin

More than 90 percent of people who are avoiding the use of penicillins are doing so needlessly.


Since the early 1940s, penicillin — a group of antibiotics that attacks a range of bacteria — has been widely prescribed by doctors for the treatment of many common, as well as more serious, infections. As the first line of treatment for many infections, penicillin works by interfering with bacteria cell walls and is so commonly used, in fact, that most Americans will have had at least one course of the drug by the time they are adults.

Just the facts

Simply put, the discovery and manufacturing of penicillin changed the face of medicine. And while these drugs have saved millions of lives over the years, many people don’t receive the benefits of this treatment because of a penicillin allergy on their medical record. In fact, about 10 percent of the U.S. population (more than 30 million people) has an allergy to penicillin listed in their medical records, when in actuality, less than 1 percent of people are dangerously allergic to the drug. Many people with a documented penicillin allergy have never actually had the condition. It could be listed on a person’s medical record because he or she had a reaction at some point but not a serious one.

A true penicillin allergy is an abnormal reaction of your immune system to the drug. Common signs and symptoms of the allergy include hives, rashes and itching, with the most severe reaction including anaphylaxis, a life-threatening condition that affects multiple body systems.

Considering the fact that less than 1 percent of the population has a true penicillin allergy, and that those who do will naturally lose the allergy over a period of five to 10 years, more than 90 percent of people avoiding the use of penicillins are doing so needlessly.

There’s a test for that

So how do you know if you have a true penicillin allergy? Sensitive testing is available that allows allergy specialists to determine whether it’s safe for individuals to use penicillin. Such testing is incredibly important for a number of reasons:

■ Second-line antibiotics may not work as well. These medicines are used when the first-line therapy (or preferred treatment) cannot be used due to allergy, side effects or lack of availability.
■ Different antibiotics may be associated with more side effects. Those side effects include, but are not limited to, nausea, vomiting, diarrhea, stomach pain, headache and rash. Some antibiotics may produce more serious side effects like abnormal heart rhythm or rupture of tendons.
■ People who are admitted to the hospital with a listing of a penicillin allergy have worse outcomes. These outcomes can include longer hospital stays and even higher risk of death.
■ Patients with a listing of penicillin allergy are also more likely to have antibiotic-resistant bacteria — which can include methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile (C. Diff), and Vancomycin-resistant enterococi (VRE) — and stems, in part, from using different antibiotics that are broad spectrum or not as effective.

It’s important to remember that while antibiotics such as penicillin aren’t always the answer, antibiotics can save lives and when a patient truly needs them, the benefits of the drug usually outweigh the risks of potential side effects. •SCM


Faoud Ishmael, MD, Ph.D., is a board-certified allergy and immunology physician with Mount Nittany Physician Group Allergy & Immunology and offers particular expertise in allergy management and testing, including testing for allergies related to foods and medicines.

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