What does the indication "no substitutions" on a prescription signify?

The indication "no substitutions" on a prescription signifies that a specific brand of medication is required for treatment. This directive means that the healthcare provider believes that a particular brand formulation is essential for the patient's treatment due to efficacy, safety, or other clinical reasons. Such a stipulation may be necessary when there are concerns regarding different formulations of the drug that could affect how the patient responds to the treatment.

In contrast, the other options do not align with this specific directive. For example, a medication being generic does not require a "no substitutions" notice, as generics are typically interchangeable. An allergy to alternatives would necessitate more explicit documentation rather than just a general "no substitutions" mark. Additionally, a prescriber being unsure about the correct medication is not relevant to the existence of the "no substitutions" instruction; rather, this notation indicates a clear preference for a brand name medication.