A client is taking hydrocodone (Vicodin) for chronic back pain. The client has required an increase in the dose and asks whether this means he is addicted to Vicodin. The nurse should base her reply on the knowledge that:

Drug tolerance is characterized by the ability to ingest a larger dose without adverse effects and decreased sensitivity to the substance. In this scenario, the client needing an increased dose of hydrocodone to achieve the same pain relief indicates tolerance developing, not addiction. Choice B is incorrect as it describes drug dependence, where the individual is preoccupied with the drug and has a loss of control. Choice C is incorrect because addiction involves psychological behaviors related to substance use, not just physical dependence with withdrawal symptoms and tolerance. Choice D is incorrect as it refers to a dual diagnosis, which is the coexistence of substance abuse and psychiatric disorders, not the development of tolerance to a drug.