What is one primary reason a doctor might write "Dispense as Written" on a prescription?

When a doctor writes "Dispense as Written" (DAW) on a prescription, it indicates that the physician wants the patient to receive the exact medication that has been prescribed, without any substitutions. This directive is often used when a specific brand of a medication is necessary for the patient due to efficacy, allergy concerns, or potential side effects associated with generic versions.

By insisting on dispensing the medication as written, the physician ensures that the patient receives the precise formulation they believe is most effective or safest for that individual's medical situation. This can be crucial in cases where even slight variations in the drug's formulation could lead to reduced effectiveness or increased risk of adverse reactions. Therefore, the use of DAW underscores the importance of maintaining medication integrity as determined by the prescribing physician.