It is believed that only ten percent of those said to have an allergy to penicillin actually have the allergy.
"Six percent of patients registered in general practice in England and 10% of patients in the US have a penicillin allergy label in their electronic health record [1, 2]. For patients who are truly allergic it is important that these records are correct, as this safeguards against serious/deadly consequences of consuming penicillin. Penicillins have been the most common cause of drug-inducted fatal and nonfatal anaphylaxis in the US and UK, but fatalities are still rare [3, 4]. However, it is also estimated that fewer than 10% of people who have a record of penicillin allergy are likely to be truly allergic to penicillins [5] and an increase in mortality has also been associated with having a penicillin allergy record [1]."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8194168/