Penicillin Allergy

Most people who believe they have  a penicillin allergy “pass” an allergy test to the drug and can take penicillin.    Some were never allergic (symptoms attributed to the penicillin were caused by another condition) and others “outgrew” the allergy.  A simple office based test for penicillin allergy is very reliable.  It’s best to sort this out before the need develops.  Patients allergic to penicillin are also sometimes told to avoid a somewhat related category of antibiotics (cephalosporins).   If you can confirm that you’re not allergic to penicillin then you will decrease the risk from using the newer antibiotics, which are more expensive, sometimes more toxic, and may lead to bacterial resistance.  This is especially important for women of child bearing age who have a history of penicillin allergy.  Pregnant women who have silent Group B strep need to be treated and this is ideally with penicillin.  Although treatment with the third generation cephalosporin is effective for Group B strep many women with a history of PCN allergy are instead treated with Vancomycin or Clindamycin (and Clindamycin resistance is an emerging problem with Group B strep).  Dentists also often prescribe Clindamycin for penicillin-allergic patients but this alternative antibiotic may wipe out too many healthy intestinal bacteria leading to severe diarrhea (C. Dificile colitis).