September 28 is National Penicillin Allergy Day
September 28 is not a random choice. On September 28, 1928, scientist Alexander Fleming discovered penicillin, one of the medicines that changed the way we treat infections.
At Family Allergy & Asthma CARE, we think this is a great time to ask a simple question:
Are you really allergic to penicillin?
The answer may surprise you.
Most People Who Say They Are Allergic to Penicillin Actually Aren't
About 1 out of every 10 people in the United States says they are allergic to penicillin.
But when these people are properly tested, more than 9 out of 10 patients who report an allergy can actually take penicillin safely. That means that less than 1% of the population is truly allergic to penicillin, not 10%.
How can that happen?
Sometimes a person was labeled allergic as a child because they developed a rash while taking amoxicillin or penicillin. But the rash may have been caused by the infection or a virus instead of the medicine.
Other people may have had nausea, diarrhea, or another side effect. These symptoms can be unpleasant, but they do not always mean that someone has a true allergy.
And even people who once had a real penicillin allergy may lose that allergy over time.
About 80% of people with a true immediate penicillin allergy lose their sensitivity after about 10 years.
That means an allergy label from childhood—or even from many years ago—may no longer be correct.
But when these people are properly tested, more than 9 out of 10 patients who report an allergy can actually take penicillin safely. That means that less than 1% of the population is truly allergic to penicillin, not 10%.
How can that happen?
Sometimes a person was labeled allergic as a child because they developed a rash while taking amoxicillin or penicillin. But the rash may have been caused by the infection or a virus instead of the medicine.
Other people may have had nausea, diarrhea, or another side effect. These symptoms can be unpleasant, but they do not always mean that someone has a true allergy.
And even people who once had a real penicillin allergy may lose that allergy over time.
About 80% of people with a true immediate penicillin allergy lose their sensitivity after about 10 years.
That means an allergy label from childhood—or even from many years ago—may no longer be correct.
Why Does It Matter?
Years ago, doctors often said, “Don’t worry. We have plenty of other antibiotics we can give you.”
Today, we know that avoiding penicillin when you do not need to may actually affect your health.
Penicillin and related antibiotics are often the best and most targeted treatments for common infections.
Today, we know that avoiding penicillin when you do not need to may actually affect your health.
Penicillin and related antibiotics are often the best and most targeted treatments for common infections.
If your medical record says you are allergic, your doctor may have to choose a different antibiotic. That antibiotic may:
- Cost more
- Have more side effects
- Kill more of the body’s helpful bacteria
- Be less effective for certain infections
- Increase the risk of antibiotic-resistant bacteria
- Increase the risk of infections such as C. difficile
People who carry a penicillin-allergy label also tend to have longer hospital stays and more infections after surgery, and research has found an association with increased health care use and a small increase in mortality among hospitalized patients.
This is why removing an incorrect allergy from your medical record—called “delabeling”—can be an important part of your medical care.
This is why removing an incorrect allergy from your medical record—called “delabeling”—can be an important part of your medical care.
Who Should Think About Penicillin Allergy Testing?
Consider talking with an allergist if:
- You were told you were allergic to penicillin or amoxicillin as a child.
- You do not remember what your reaction was.
- Your reaction happened many years ago.
- You only remember having a mild rash or itching.
- You had nausea, diarrhea, headache, or another side effect rather than a true allergic reaction (Such as respiratory symptoms, or swelling of tongue, throat, or lips.)
- You have avoided penicillin for years because someone told you that you were allergic.
Current allergy guidelines consider many people with a mild reaction more than five years ago to be at low risk and possible candidates for a simple oral medication challenge.
People who had a severe reaction such as anaphylaxis, trouble breathing, major swelling, or certain severe skin reactions need a different type of evaluation. Your allergist will decide what testing is safest for you.
How Do Allergists Remove a Penicillin Allergy Label?
The good news is that penicillin allergy evaluation is usually safe and straightforward.
Your allergist will first talk with you about what happened when you took the medicine.
Depending on your history, there are several ways we may evaluate you.
Your allergist will first talk with you about what happened when you took the medicine.
Depending on your history, there are several ways we may evaluate you.
Sometimes no testing is needed
If your “allergy” was really a side effect—such as nausea—or if the label was placed in your chart only because a family member was allergic, an allergist may determine that you are not allergic based on your history alone.
If your “allergy” was really a side effect—such as nausea—or if the label was placed in your chart only because a family member was allergic, an allergist may determine that you are not allergic based on your history alone.
Some patients can have a simple oral challenge
If your “allergy” was really a side effect—such as nausea—or if the label was placed in your chart only because a family member was allergic, an allergist may determine that you are not allergic based on your history alone.
People with a very low-risk history may be given a dose of amoxicillin or another penicillin antibiotic in the office and watched carefully afterward.
If nothing happens, the penicillin allergy can usually be removed from the medical record. For many low-risk children, and some low-risk adults, current guidelines favor this direct oral challenge without skin testing first.
If your “allergy” was really a side effect—such as nausea—or if the label was placed in your chart only because a family member was allergic, an allergist may determine that you are not allergic based on your history alone.
People with a very low-risk history may be given a dose of amoxicillin or another penicillin antibiotic in the office and watched carefully afterward.
If nothing happens, the penicillin allergy can usually be removed from the medical record. For many low-risk children, and some low-risk adults, current guidelines favor this direct oral challenge without skin testing first.
Other patients may need skin testing first
If your history sounds more like a true immediate allergic reaction, your allergist may perform penicillin skin testing.
Tiny amounts of penicillin testing material are placed on and just under the skin. If those tests are negative, an oral dose of amoxicillin is usually given while you are observed in the office.
A negative evaluation gives strong reassurance that penicillin can be used safely in the future.
If your history sounds more like a true immediate allergic reaction, your allergist may perform penicillin skin testing.
Tiny amounts of penicillin testing material are placed on and just under the skin. If those tests are negative, an oral dose of amoxicillin is usually given while you are observed in the office.
A negative evaluation gives strong reassurance that penicillin can be used safely in the future.
One Small Test Can Make a Big Difference
An old penicillin allergy label can follow you for decades.
It may be copied from one medical record to another without anyone ever asking whether you are still allergic—or whether you were truly allergic in the first place.
An old penicillin allergy label can follow you for decades.
It may be copied from one medical record to another without anyone ever asking whether you are still allergic—or whether you were truly allergic in the first place.
National Penicillin Allergy Day is a good reminder to find out.
If your penicillin reaction happened many years ago, or you are not even sure what happened, ask us whether penicillin allergy testing or an oral challenge may be right for you.
Getting the correct answer today could give your doctors better—and sometimes safer—antibiotic choices for the rest of your life. An old penicillin allergy label can follow you for decades. It may be copied from one medical record to another without anyone ever asking whether you are still allergic—or whether you were truly allergic in the first place.
If your penicillin reaction happened many years ago, or you are not even sure what happened, ask us whether penicillin allergy testing or an oral challenge may be right for you.
Getting the correct answer today could give your doctors better—and sometimes safer—antibiotic choices for the rest of your life. An old penicillin allergy label can follow you for decades. It may be copied from one medical record to another without anyone ever asking whether you are still allergic—or whether you were truly allergic in the first place.
References
- Centers for Disease Control and Prevention. Penicillin Allergy – STI Treatment Guidelines.
- Centers for Disease Control and Prevention. Is It Really a Penicillin Allergy? Evaluation and Diagnosis of Penicillin Allergy for Healthcare Professionals.
- American Academy of Allergy, Asthma & Immunology. Penicillin Allergy—What Do You Need to Know?
- American Academy of Allergy, Asthma & Immunology. Penicillin Allergy Evaluation Should Be Performed Proactively in Patients with a Penicillin Allergy Label.
- National Penicillin Allergy Day. September 28—National Penicillin Allergy Day.