Final answer:
A prescription with a 'do not fill until XX/XX/XXXX' notation generally should not be filled more than 90 days after being written for controlled substances, but this can vary based on medication type and state law.
Step-by-step explanation:
The prescription notation "do not fill until XX/XX/XXXX" is a legal instruction used to specify the earliest date on which a pharmacy can dispense a medication. The allowance for filling a prescription with such a future use notation varies by the specific medication, state laws, and the type of medication prescribed, particularly if the prescription is for controlled substances. For many medications, the prescription can typically be filled within 30 to 90 days from the date it was written, according to state regulations. However, for controlled substances, different schedule drugs have specific time restrictions. For example, Schedule II controlled substances prescriptions may not be filled more than 90 days after the prescription date. It's important to consult specific state laws and regulations as they can vary. Additionally, it is vital to clarify whether a future use notation is applicable and allowable for the particular prescription in question. Thus, in the context of controlled substances, if a prescription says "do not fill until" with a future date, it generally should not be filled more than 90 days after the prescription date, but this can substantially differ based on state law and medication.