What is one of the essential components of a prescription label?

One of the essential components of a prescription label is the drug dosage. This information is crucial as it provides specific instructions to the patient on how much of the medication to take and how often. Proper dosage is vital for the safety and effectiveness of the medication; incorrect dosages can lead to therapeutic failures or adverse drug reactions.

While other elements like the patient's phone number, pharmacy's address, and the prescriber's name are important for various reasons—such as enabling contact, identifying the dispensing pharmacy, and confirming who prescribed the medication—they do not play as pivotal a role in patient safety and medication efficacy as the drug dosage does. Therefore, providing clear and accurate dosage information is a core requirement for prescription labeling to ensure proper patient understanding and adherence to treatment regimens.