A nurse is assessing a client for a substance use disorder. The client exhibits yawning, pupillary dilation, rhinorrhea, and reports muscle cramps. The nurse should suspect that the client is withdrawing from which of the following substances?

Choice A reason: Alcohol withdrawal is primarily associated with central nervous system hyperexcitability due to abrupt cessation of a depressant substance. Expected findings include tremors, diaphoresis, tachycardia, hypertension, anxiety, insomnia, nausea, vomiting, seizures, and in severe cases delirium tremens characterized by confusion, hallucinations, and autonomic instability. Pupillary dilation, yawning, rhinorrhea, and muscle cramps are not hallmark features of alcohol withdrawal, making this option inconsistent with the client’s presentation. Choice B reason: Heroin is an opioid, and opioid withdrawal produces a predictable cluster of symptoms related to rebound autonomic and neuromuscular hyperactivity. Classic manifestations include yawning, lacrimation, rhinorrhea, pupillary dilation (mydriasis), piloerection, muscle and bone pain, abdominal cramping, diarrhea, nausea, and restlessness. Muscle cramps and flu-like symptoms are particularly characteristic. Although opioid withdrawal is extremely uncomfortable, it is typically not life-threatening. The client’s symptoms align precisely with opioid withdrawal, making this the correct answer. Choice C reason: Cannabis withdrawal is generally mild and primarily psychological rather than severe physical withdrawal. Common findings include irritability, anxiety, insomnia, decreased appetite, restlessness, depressed mood, and headache. Autonomic signs such as rhinorrhea, yawning, pupillary dilation, and muscle cramps are not typical features of cannabis withdrawal, which rules out this option. Choice D reason: Cocaine withdrawal is characterized by a “crash” phase due to depletion of dopamine and other neurotransmitters. Expected manifestations include fatigue, hypersomnia, increased appetite, depression, anxiety, vivid dreams, and psychomotor retardation. Physical signs such as yawning, rhinorrhea, muscle cramps, and pupillary dilation are not characteristic of cocaine withdrawal. Therefore, this option does not match the client’s symptoms.