February 2019 Pharmacy Update

Antibiotic Resistance: Assessing Antibiotic Allergies


As you may already be involved in various antibiotic stewardship initiatives in your practice, it is also imperative to highlight the importance of properly assessing and reassessing patient-reported allergies to antibiotics.


  1. Approximately 10% of Americans believe they have a penicillin allergy 1

    • Less than 1% of the population are truly allergic to penicillins

  2. 90% of patients labeled as penicillin-allergic were able to tolerate penicillin when evaluated 2
    • No true IgE-mediated reactions when tested by board-certified allergist
  3. About 80% of patients with true, documented (IgE-mediated) penicillin allergy lose sensitivity after 10 years 1
  4. When patients are listed as having a penicillin allergy, prescribers often prescribe broad-spectrum antibiotics, which are often costlier and may be suboptimal therapy 1,3
    • Leads to more adverse effects, antibiotic resistance, and “alert fatigue” for prescribers
  5. MYTH: Patients with a penicillin allergy will also experience allergic reactions with cephalosporins due to cross-reactivity
  6. FACT: Cross-reactivity rate between penicillins and cephalosporins is 3% 2

What can I do?

  1. Ask the right questions when conducting history and physicals for patients who report and have reported penicillin allergies
    • Document reaction type, date, and time of onset
    • See attached* for recommended questions to ask during allergy assessment
    • Update patient profile and EHR
  2. Counsel patients when prescribing antibiotics on possible reactions and when to seek MD or 911
    • ex: Upset stomach is a common side effect that usually goes away after a few doses and can be prevented if taken with food
  3. Refer patient to allergist for skin testing and challenge dose when appropriate
    • If skin testing is positive, use another antibiotic or refer for desensitization if necessary

 *Email SVHP Clinical Pharmacist for Allergy Questionnaire




1. Joint Task Force on Practice Parameters representing the American Academy of Allergy, Asthma and Immunology; American College of Allergy, Asthma and Immunology; Joint Council of Allergy, Asthma and Immunology. Drug allergy: an updated practice parameter. Ann Allergy Asthma Immunol. 2010 Oct;105(4):259-273.
2. Gonzalez-Estrada A, Radojicic C. Penicillin allergy: a practical guide for clinicians. Cleve Clin J Med 2015;82(5):295–300 [PubMed: 25973877].
3. Albin S, Agarwal S. Prevalence and characteristics of reported penicillin allergy in an urban outpatient adult population. Allergy Asthmas Proc. 2014;35(6):489-494. doi: 10.2500/aap.2014.35.3791