Penicillin allergy diagnosis is often false

The diagnosis of a penicillin allergy is rarely preceded by a thorough diagnostic procedure. The diagnosis is given when symptoms occur following treatment with penicillin, such as redness or swelling of the skin, itching, nausea or circulatory problems. But all these symptoms are not necessarily linked to the antibiotic. They can also be caused by the pathogen itself or by the disease.

When a penicillin allergy is suspected, there are considerable consequences. If a new infection occurs, penicillin antibiotics cannot be administered. “There are real disadvantages to taking other antibiotics, but doctors and patients are not sufficiently aware of this”, says DGI president Gerd Fätkenheuer, who states that other substance categories are less effective or associated with more side effects. They also increase the likelihood that the bacteria will develop resistance to antibiotics, which means that the antibiotic will become ineffective.

The conclusion is that a penicillin allergy must be confirmed with laboratory tests.

Half of antibiotic prescriptions do more harm than good

Eighty-five percent of all antibiotics are prescribed on an outpatient basis, and are therefore not taken by hospital patients but instead delivered by a patient’s registered physician. The most common reason for antibiotic therapy is acute inflammation of the upper respiratory tract, when in fact most of these infections are caused by viruses, which cannot be treated with antibiotics. Antibiotics only help in cases of bacterial infection.

According to a report (GERMAP 2015) from the German Federal Office of Consumer Protection and Food Safety, as many as 70 per cent of children under five received an antibiotic in 2010.

The Drug Commission of the German Medical Association (AkdÄ) believes that one in two antibiotic prescriptions are unjustified (Feldmeier G et al. 2018). As examples, the association cites the lack of effectiveness against viral infections, the prescription of a wrong substance, and insufficient dosage or duration of therapy.

The association advises against automatically prescribing any drug for respiratory tract infections. Most illnesses improve on their own in a few days with common sense measures such as rest, drinking plenty of fluids, and taking painkillers for muscle aches if necessary.

To be sure, get an allergy test

A penicillin allergy can be confirmed with certainty through a series of diagnostic tests. First it must be determined which substance caused the suspected allergic reaction. This is not always easy, since in many cases the antibiotic was administered during childhood and the patient cannot recall exactly what it was (Trubiano JA et al. 2017). If the skin test results are inconclusive, a test to check the blood level of allergen-specific immunoglobulin E and a provocation test should provide an answer.

A recent review (Shenoy SE et al. 2019) concluded that 95 per cent of all people assumed to be allergic to penicillin can safely receive penicillin treatment again. The study provides the following explanations: first, most allergy diagnoses are made during childhood and are based on the observations of the parents, and an allergy test was never carried out. Second, 80 per cent of penicillin allergies can no longer be detected after ten years.

“People who think they have a penicillin allergy and parents of children who are assumed to have a penicillin allergy should question the diagnosis and get further testing if necessary”, says Kimberly Blumenthal of Massachusetts General Hospital in Boston, Massachusetts, one of the co-authors of the review.

Min Lee, a paediatrician at the University of Texas Southwestern in Dallas, recommends the ideal time for this in the university’s MedBlog: when a child transitions over to adult medical care, it’s “a good time to get the label removed from his or her health records.”