What warning must be included on addictive medications according to pharmaceutical regulations?

The requirement to include a warning about the potential habit-forming nature of certain medications stems from the understanding of their pharmacological effects and the risk factors associated with misuse and addiction. Medications classified as addictive, particularly opioids and certain benzodiazepines, can lead to physical dependence and addiction in patients if not used properly.

Including the warning "may be habit forming" explicitly informs patients and healthcare providers of the serious risks involved and encourages responsible prescribing and usage practices. This warning serves as a critical reminder for patients to be aware of their medication's potential for misuse and to engage in discussions with their healthcare providers regarding safe usage and alternative treatment options when necessary.

The other options, while relevant in certain contexts, do not specifically address the core concern of addiction and dependence associated with these medications. For instance, a warning about drowsiness is pertinent but does not encapsulate the broader implications of habit formation. Thus, the emphasis on habit formation aligns directly with the objectives of regulatory guidelines aimed at mitigating the risks associated with these substances.