What are the symptoms of opioid (narcotic analgesic) overdose?

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Last updated: April 11, 2025View editorial policy

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From the Guidelines

Opioid overdose symptoms include central nervous system depression and respiratory depression, which can progress to cardiac arrest if left untreated, as stated in the 2024 American Heart Association and American Red Cross guidelines for first aid 1. These symptoms can manifest as sleepiness, unresponsiveness, slowed breathing, and eventually stopped breathing. It is essential to recognize these symptoms promptly and take immediate action.

  • Key symptoms of opioid overdose include:
    • Central nervous system depression (sleepiness, unresponsiveness)
    • Respiratory depression (slowed and stopped breathing)
    • Cardiac arrest (if left untreated) According to the guidelines, naloxone is an antidote that can reverse the effects of opioid overdose, restoring consciousness and breathing 1.
  • Naloxone administration is crucial in responding to an opioid overdose, and it can be administered by multiple routes, including a nasal spray available in the United States without a prescription. If someone is suspected to be experiencing an opioid overdose, it is vital to call 911 immediately and administer naloxone if available, following the Opioid-Associated Emergency for Lay Responders Algorithm 1.
  • Other important steps in responding to an opioid overdose include positioning the person on their side to prevent choking if they vomit and continuing to monitor the person as naloxone wears off after 30-90 minutes, as multiple doses may be needed.

From the Research

Opioids Overdose Symptoms

  • Opioid-induced respiratory depression is the primary cause of death in opioid overdose, resulting from the neural depression of respiratory drive, decreased level of consciousness, and obstructive sleep apnea, leading to ventilatory insufficiency 2.
  • The symptoms of opioid overdose can include severe respiratory depression (SRD), which is defined as the administration of either naloxone or endotracheal intubation (ETI) 3.
  • The risk factors for severe respiratory depression from prescription opioid overdose include opioid misuse, increased age, and the specific opioid medication involved, with fentanyl having a high relative risk of SRD (83.3%) and codeine having a low relative risk (3.6%) 3.
  • The mechanisms of opioid-induced respiratory depression involve multiple sites in the brainstem, including the preBötzinger complex (preBötC), the pontine Kölliker-Fuse and adjacent parabrachial nuclei (KF/PBN), and the dorsal respiratory group, which can independently exert a depressive effect on breathing 2.
  • Naloxone is currently the only available treatment for reversing the negative effects of opioids, including respiratory depression, but its effectiveness can vary depending on the pharmacokinetics and pharmacodynamics of the opioid that was overdosed, and it may not be efficacious against high-potency opioids such as fentanyl and fentanyl analogs 4, 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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