What is the first-line treatment option for a 24-year-old woman found lethargic with a history of opioid use?

Naloxone is the first-line treatment option in cases of suspected opioid overdose. This medication is an opioid antagonist that rapidly reverses the effects of opioids, effectively restoring respiratory function and consciousness in someone who has become lethargic or unresponsive due to opioid use. Given that the individual in question has a history of opioid use and presents with lethargy, it is crucial to administer Naloxone quickly to counteract the opioid's life-threatening effects.

Other options, such as atropine, are not indicated for opioid overdose and primarily function as an anticholinergic agent, which addresses different conditions. A CT of the head without contrast would be useful in ruling out intracranial pathology in lethargy cases but does not address the immediate concern of opioid toxicity. Flumazenil, a benzodiazepine antagonist, could precipitate seizures in someone who has taken multiple substances, including opioids. Therefore, Naloxone remains the definitive choice for reversing opioid intoxication and restoring normal respiratory drive in this scenario.