February 1, 2019
Penicillin was the original “wonder drug”—but, today, people are wondering why, for more than half a century, doctors have warned them it’s contraindicated for their care.
Discovered in 1928 and found to “miraculously” cure infections by 1942, penicillin was the first antibiotic that many Baby Boomers were prescribed as children. However, that first dose of penicillin also turned out to be the last for many youngsters—who broke out in bumps or rashes that were diagnosed as allergic reactions.
Now there is a different school of thought. In fact, according to a study posted by the Journal of the American Medical Association in January, fully 19 out of 20 people who have been told they are allergic to penicillin actually can tolerate it well.
Indeed, The New York Times reported on January 22, millions of Americans whose medical histories document their penicillin sensitivities are not actually allergic. But they are steered away from using some of the safest, most effective antibiotics—relying instead on substitutes that are often pricier, less effective, and more likely to cause complications such as antibiotic-resistant infections.
Experts in allergy and infectious disease, including the paper’s authors, are now urging patients to ask doctors to review their medical history and re-evaluate whether they truly have a penicillin allergy.
The evaluation—which may require allergy skin testing and ideally should be done while people are healthy— is especially important, The Times reports, for pregnant women, people with cancer and those in long-term care, and anyone anticipating surgery or being treated for a sexually transmitted infection.
“When you have a true infection that needs to be treated, the physician will see you have the allergy and not question it,” said Dr. Erica S. Shenoy, an author of the study, and an infectious diseases specialist who is s on the staff of Harvard Medical School of Massachusetts General Hospital.
The review was carried out with input from the boards of three professional medical organizations: the American Academy of Allergy, Asthma and Immunology; the Infectious Diseases Society of America; and the Society for Healthcare Epidemiology of America. All three groups endorsed the findings.
There is no question that some patients have potentially life-threatening allergic reactions to penicillin, but the label appears to have been applied far too broadly, experts say. About 10% of Americans report having a penicillin allergy, and the rate is even higher among older people and hospital patients—15% of whom have a documented penicillin allergy.
But studies that have gone back and conducted allergy skin testing on patients whose medical records list a penicillin allergy have found that the overwhelming majority test negative. A 2017 review of two dozen studies of hospitalized patients found that over all, 95 percent tested negative for penicillin-specific immunoglobulin E, or IgE, antibodies, a sign of true allergy.
“We used to say nine out of 10 people who report a penicillin allergy are skin-test negative. Now it looks more like 19 out of 20,” Dr. David Lang, president-elect of the American Academy of Allergy, Asthma and Immunology and chairman of allergy and immunology in the respiratory institute at the Cleveland Clinic, told the Times.
What’s more, the researchers say, many people who have avoided penicillin for a decade or more after a true, severe allergic reaction will not experience that reaction again.
“Even for those with true allergy, it can wane,” said Dr. Kimberly Blumenthal, the review’s senior author, who is an allergist and an assistant professor at Harvard Medical School. “We don’t really understand this, but once you’ve proven you’re tolerant, you go back to having the same risk as someone who never had an allergy” to penicillin.
Finally, the researchers warn, don’t challenge yourself to penicillin on your own. Patients who have been told they’re allergic to penicillin should talk to their doctors, who should take a careful history and review the symptoms of the reaction.
If the past reaction to penicillin included symptoms like headache, nausea, vomiting and itching, or the diagnosis was made based on a family history of the allergy, the patient is considered low-risk and may be able to take a first dose of penicillin or a related antibiotic, such as amoxicillin, under medical observation.
If the past reaction included hives, a rash, swelling, or shortness of breath, patients should have penicillin skin test, followed by a second test that places the reagent under the skin if the first test is negative. If both tests are negative, the patient is unlikely to be allergic to penicillin, and an oral dose may be given under observation to confirm
Research contact: @nytimes