Correcting a common, costly misconception about penicillin allergies
More than 90% of reported penicillin allergies are not true allergies. A new enterprise-wise initiative, Penicillin Allergy Delabeling using the PEN-FAST Calculator, recently has been approved as a standardized best practice to safely remove incorrect allergy labels from patient charts.
“This project is very important to me, as I strongly agree that many patients are mislabeled with a penicillin allergy,” said Marisa Echaniz, MD, Hospital Medicine and Saint Joseph’s physician champion for this initiative. “This mislabeling creates several downstream challenges.”
Echaniz lists four quality-of-care and access-to-care challenges specifically:
Mislabeling complicates antibiotic selection.
It increases length of stay.
It raises costs for both the hospital and patients (who may be prescribed more expensive alternatives).
It drives up infectious disease consults when more unusual antibiotic options must be explored.
In addressing these issues, penicillin delabeling is a high-value, low-risk intervention that improves care quality and reduces harm to patients and organizational and patient costs.
How does the delabeling process work using the PEN-FAST Calculation?
Risk assessment: A healthcare professional reviews the history of the reaction to determine risk.
PEN-FAST score of <3 points equals low‑risk: Low probability of a positive penicillin oral challenge test (<5% risk)
Direct oral challenge: For low-risk patients, a single dose of amoxicillin is administered in a hospital setting to verify tolerance.
Removal: If the patient tolerates the oral challenge, the allergy label is removed from the medical record, and the patient is notified.
Epic workflow support
Epic supports the penicillin allergy delabeling process through standardized pharmacist workflows. Pharmacists document the PEN‑FAST score in the Pharmacy Minimum Data flowsheet, which can then be pulled directly into the allergy comments using the smart phrase .rxpenfast.
Patients who meet low‑risk criteria based on the PEN‑FAST score are eligible for evaluation using the Intermountain Penicillin Allergy Challenge order set, supporting safe delabeling when clinically appropriate.
Patient education resources
Penicillin allergy fact sheets:
Patient safety and outcomes
Alternative antibiotics carry:
2–3 times higher risk of C. difficile.
Higher rates of acute kidney injury and drug toxicity.
Less-effective treatment for common infections.
Delabeling enables narrower, first‑line, guideline‑recommended therapy with better efficacy and fewer side effects.
Unconfirmed allergy labels lead to the use of broader-spectrum antibiotics, which can cause increased side effects, antibiotic resistance and poorer health outcomes.
Cost and impact
$1,500–$4,000 savings per inpatient by avoiding higher cost alternative antibiotics, reducing length of stay, and reducing antibiotic-related and infection-related complications
One‑time delabeling provides lifelong benefit across future encounters
What this means for daily practice
Simpler antibiotic choices for hospitalists, nurses, and pharmacists
More accurate allergy lists and safer medication administration
Strong alignment with antimicrobial stewardship, quality and value‑based care goals
Additional resources
More information is available on the Antimicrobial Stewardship website.
Questions? Contact Wyatt, Whitney Buckel, PharmD, or Robert Silge, MD.