Why might a pharmacist refuse to fill a prescription?

A pharmacist might refuse to fill a prescription if the dosage is unclear because clarity in medication dosages is critical for patient safety. Ambiguous or improperly written dosages can lead to significant risks, including underdosing or overdosing, both of which can have serious health implications for the patient. Pharmacists are responsible for ensuring that medications are dispensed correctly and safely, and any uncertainty regarding dosages necessitates clarification with the prescriber before proceeding to fill the medication.

In terms of the other options, a prescription written by a known prescriber does not inherently present a reason to refuse to fill it; pharmacists often know which prescribers are legitimate and trustworthy. If a patient requests a refill, the pharmacist would typically review the prescription history rather than refuse outright, as refills are part of the normal dispensing process if authorized. While a pharmacy being out of stock might delay the filling of a prescription, it does not constitute a reason to refuse to fill it; the pharmacist would usually try to order the medication or provide alternatives if possible. Thus, it's the lack of clarity regarding the dosage that makes this the most critical reason for refusing to fill a prescription.