Which of the following is a characteristic of a dangerous drug?

A dangerous drug is defined as a substance that poses a risk to health and safety when used improperly, particularly without the guidance of a healthcare professional. The correct choice highlights that a dangerous drug is unsafe for self-medication and not included in specific penalty groups. This indicates that such drugs may lack proper regulation and oversight, which can lead to misuse or adverse effects.

The idea that certain drugs could be safe for self-medication contradicts the inherent risks associated with dangerous drugs. While some substances may be available without prescription and for self-medication, dangerous drugs typically require professional oversight to ensure safe usage. Being excluded from specific penalty groups implies a broader classification where the safety profile is a concern, rather than being encompassed in regulated tiers where infection control and safety measures are in place.

In contrast, drugs listed in Schedules I through V are classified based on their potential for abuse and medical utility, which does not inherently categorize them as dangerous drugs. Additionally, availability over-the-counter without restrictions would suggest that the substance has an established safety profile, negating its classification as a dangerous drug.