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Many people think they’re allergic to penicillin, but experts say most of the population is not allergic at all. Allergist and immunologist Luis Saca, MD, implemented a new program at Loma Linda University Health to test for patients’ penicillin allergy and hopefully decrease the unnecessary use of broad-spectrum antibiotics.

According to the CDC, approximately 10% of U.S. patients report having a penicillin allergy. Realistically, however, fewer than 1% of the population is truly allergic to penicillin, as noted in the same CDC report. This allergy limits an individual’s access to many beneficial medications that are penicillin derivatives. Penicillin allergy patients must take broad-spectrum antibiotics that can increase healthcare costs and antibiotic resistance.

Saca says reactions to the drug in childhood cause many individuals to think they are allergic through adulthood. “The allergic reaction is not for life,” he says. “We now know that if someone has not been exposed to penicillin in over five years, there is about an 80% chance that the allergy is out of their system.”

Many patients also experience side effects and label it an allergy. Nausea, vomiting, and abdominal pain are just a few common side effects — not allergic reactions. Someone experiencing a true allergic reaction to penicillin may have a cough, shortness of breath, itchiness, or a rash. These are indicators of a type-1 hypersensitivity reaction in someone whose immune system developed an IgE antibody against a soluble antigen (eg., penicillin).

Saca says referrals to allergy and immunology will receive a progressive three-step test in one doctor’s visit.

  1. Skin prick test. A positive reaction indicating an allergy will cause a red, itchy, raised bump. Patients with no reaction move to the next step.
  2. Intradermal test. The faculty will then inject a small amount of solution under the skin of the forearm to create a small bump. Growth indicates a positive reaction. The patient will move to the final test if no growth is observed.
  3. Oral test. Patients will receive amoxicillin in the office and are closely monitored by faculty for 45 to 60 minutes. Saca says if the first two tests are negative, the oral test is likely also negative.

Receiving negative results for all tests allows Saca to remove the penicillin allergy from the patient’s chart and restore their healthcare options.

To find out if your penicillin allergy is no longer in your system, make an appointment with your primary care doctor and ask for a referral to Allergy and Immunology.