Final answer:
The number of patients reporting a PCN allergy who actually have a PCN allergy based on a major review can vary. It is important to consult a healthcare professional for accurate diagnosis and management.
Step-by-step explanation:
The number of patients reporting a PCN allergy who actually have a PCN allergy based on a major review can vary. It is important to note that the accuracy of diagnosing a PCN allergy can be challenging and requires comprehensive testing. Various studies have reported different prevalence rates of PCN allergies, ranging from 1% to 10% among patients who claim to have an allergy.