Do you have a TRUE penicillin allergy?

I often hear from patients that they have a penicillin allergy.  Penicillin allergy is the most commonly documented drug allergy in medical records.  Approximately 10% of patients report a penicillin allergy.  HOWEVER, up to 90% of patients with a reported penicillin allergy tolerate penicillin on allergy testing. 

What is the downside of having penicillin allergy reported when indeed you are not?! When penicillins cannot be used for an infection, patients are often started on an alternative broader-spectrum antibiotic with potentially poorer effectiveness and less favorable safety profile.  When patients are on broader-spectrum antibiotics this can lead to increased multidrug-resistant organism, treatment failures and increasing healthcare costs and longer hospitalizations.

There is a validated clinical prediction rule for penicillin allergy.  The PEN-FAST (penicillin allergy, five or fewer years ago, anaphylaxis/angioedema, severe, treatment) rule was made from a study of 600+ patients in Australia.  There were five independent predictors identified that are important.  The risk factors to include in the clinical prediction rule are:

Allergy event occurred five or less years ago (2 points)

Anaphylaxis/angioedema or severe adverse skin reaction (2 points)

Treatment required of penicillin allergy (1 point)

Total scoring ranged from 0 to 5 points.

If patient has 0 points, there is a 0.6% risk of really having a significant penicillin allergy.

If the patient has 1 or 2 points, there is 5% risk

If the patient has 3 points, there is a 19% risk

If the patient has 4 or 5 points, there is a 53% risk of penicillin allergy.

Consider seeing a physician who specializes in allergy testing.