Risk Factors for Penicillin Allergy:

History of previous reaction to penicillin

- Patients are six times more likely to react on subsequent exposure than patients with a negative history.

 

Route of administration

- More likely with the parenteral route than with the oral route.

 

Age

- Most common in patients between 20 and 49 years. True penicillin allergy is uncommon in the pediatric population.

NB:  Anaphylaxis to β-lactam antibiotics is not genetic, i.e. it does not run in families.