What distinguishes a prescription medication from an over-the-counter (OTC) medication?

A prescription medication is distinguished from an over-the-counter (OTC) medication primarily by the requirement for authorization from a licensed healthcare provider. This necessity for a prescription indicates that a healthcare professional has evaluated the patient's condition and determined that the medication is appropriate for their specific needs.

Prescription medications often have more stringent safety profiles, potential side effects, or require monitoring for efficacy and safety that necessitates professional oversight. This is not the case with OTC medications, which are deemed safe and effective for use without a prescription and can be readily obtained by consumers.

The other choices present factors that do not validly distinguish between prescription and OTC medications. The cost of medications can vary widely and is not a definitive measure of their classification. The availability of OTC medications is typically not limited by quantity, allowing consumers to purchase as needed. Lastly, the effectiveness of medications cannot be broadly categorized in this manner, as many OTC medications can be quite effective for certain conditions, just as some prescription medications may not be the most potent option for others.