How Long Should Patients Be Observed After Opioid Overdose?
Date First Published:
November 29, 2025
Last Updated:
November 29, 2025
Report by:
Zain Alajjouri MD, Mariah Barnes MD, Senior EM resident, EM Faculty (Corewell Health/Michigan State University Emergency Medicine Residency Program)
Search checked by:
Jeffrey Jones MD, Research Director
Three-Part Question:
How long should [adult patients with suspected acute opioid overdose] be [monitored in the emergency department] to [prevent adverse events]?
Clinical Scenario:
Paramedics were called to the home of a woman found lying on the floor unresponsive. The patient's family stated that she may have used drugs. Her Glasgow Coma Score was 5. The patient's pupils were constricted and non-reactive. Glucose level was 84. An IV was established and the patient received a total of 5 mg of Narcan en route to the hospital. By the time the patient arrived at the hospital, she had become alert and responsive. The patient's vital signs were stable and her physical exam was normal. She told the ED nurse that she had smoked heroin. A urine drug screen was performed and was positive for both opiates and cocaine. As the treating physician you consider how long you should monitor the patient before discharge from the ED.
Search Strategy:
Medline 1966-09/25 using PubMed, Cochrane Library (2025), and Embase
Search Details:
((opioid poisoning) OR (opioid overdose) AND ((patient discharge) OR (patient monitoring)). Limit to adults and English language
Outcome:
49 total articles were identified; four addressed the clinical question.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Hospital Observation Upon Reversal (HOUR) With Naloxone: A Prospective Clinical Prediction Rule Validation Study. Clemency BM, Eggleston W, Shaw EW, Cheung M, Pokoj NS, Manka MA, Giordano DJ, Serafin L, et al. January 2019 USA | 538 adults were observed for one hour after administration of prehospital naloxone. | Prospective observational study to determine if clinical judgment and/or a six-component clinical prediction rule applied 1 hour after prehospital naloxone administration for suspected opioid overdose could predict which patients would not have an adverse event (AE) in the first 24 hours. | The sensitivity, specificity, positive predictive value, and negative predictive value for the prediction rule, clinical judgment, the prediction rule in combination with clinical judgment, and each of the six components of the prediction rule. | Adverse events occurred in 82 (15.4%) patients. The clinical prediction rule had a sensitivity of 84.1% (95% confidence interval [CI] = 76.2%–92.1%), a specificity of 62.1% (95% CI = 57.6%–66.5%), and a negative predictive value of 95.6% (95% CI = 93.3%–97.9%). Only one patient with a normal 1-hour evaluation subsequently received additional naloxone following a presumed heroin overdose. | This study did not limit its inclusion criteria based on the drug used or route of administration, there was no long term follow-up, some of the patients treated with naloxone for presumed opioid overdose may not have actually overdosed on opioids, and the prediction rule and provider impression had similar performance characteristics. |
| Risk of Delayed Intubation After Presumed Opioid Overdose in the Emergency Department McCabe DJ, Gibbs H, Pratt AA, et al. June 2025 USA | 1,591 patients presenting to the emergency department with acute opioid overdose | Prospective, multi-institutional study assessed the risk of “delayed intubation" | Whether the patient received delayed intubation following | Of the 1,591 patients included, only 9 (0.6%) required delayed intubation. Eight of these patients had nonrespiratoryrelated conditions contributing to the need for intubation. One patient only had respiratory-related conditions, had respiratory | Data collected came from several sites throughout the United States, but those are not nationally representative. The limited number of patients with delayed intubation restricted the statistical analyses that could be conducted. Significant numbers of patients in were excluded for various reasons, increasing bias. |
| suspected opioid overdose, defined as endotracheal | acidosis, and received a total of 6.4 mg naloxone before intubation. | ||||
| intubation occurring more than 4 hours after arrival at a | |||||
| hospital. | |||||
| Early discharge of patients with presumed opioid overdose: development of a clinical prediction rule Christenson J, Etherington J, Grafstein E, et al. October 2000 Canada | 573 patients who received naloxone for known or presumed opioid overdose | Patients were classified into two groups: those with adverse events within 24 hours and those without. Using classification and regression tree methodology, a decision rule was developed to predict safe discharge. | Sensitivity and specificity of clinical decision rule developed to predict safe discharge | The clinical prediction rule had a sensitivity of 99% (95% CI = 96% to 100%) and a specificity of 40% (95% CI = 36% to 45%). Patients with presumed opioid overdose can be safely discharged one hour after naloxone administration if they: 1) can mobilize as usual; 2) have oxygen saturation on room air of >92%; 3) have a respiratory rate >10 breaths/min and 35.0°C and 50 beats/min and <100 beats/min; and 6) have a Glasgow Coma Scale score of 15. | Convenience sample, the number of adverse events after presumed opioid overdose was lower than predicted decreasing the 95% confidence limit on the sensitivity to predict adverse events, no validation study, limited phone follow-up of patients, and opioid overdose was not confirmed. |
| Do heroin overdose patients require observation after receiving naloxone? Willman MW, Liss DB, Schwarz ES, et al February 2017 USA | Adult patients presenting to the ED following a heroin overdose who received naloxone | Systematic review consisting of five articles addressing the duration of ED observation required for patients treated with naloxone for opioid overdoses |
How long to observe patients in the ED after receiving naloxone. | Patients who are able to ambulate, have a GCS of 15, | Variability in the reporting of less serious complications due to heterogeneity in the definitions of adverse events and a lack of described clinical significance. |
| have no features of opioid intoxication and have normal vital | |||||
| signs may be allowed to leave after one hour as serious | |||||
| adverse events or significant rebound opioid toxicity is | |||||
| unlikely. |
Author Commentary:
Over 1 million ED visits yearly are attributed to opioid-related diagnoses. These articles had some weaknesses, such as possible selection bias since there was no laboratory confirmation of opioid intoxication. This may have over-estimated the sensitivity/NPV of the predication rules. It was interesting that provider judgment had a similar NPV, and a combination of provider judgement and these prediction rules would allow clinicians to safely discharge patients.
Bottom Line:
There is sufficient evidence to support that in the case of adult patients with suspected acute opioid overdose, patients can be safely discharged safely if they meet St.Paul’s/Hour Rule criteria (normal vital signs, GCS 15, able to ambulate).
Level of Evidence:
Level 2: Studies considered were neither 1 or 3
References:
- Clemency BM, Eggleston W, Shaw EW, Cheung M, Pokoj NS, Manka MA, Giordano DJ, Serafin L, et al.. Hospital Observation Upon Reversal (HOUR) With Naloxone: A Prospective Clinical Prediction Rule Validation Study.
- McCabe DJ, Gibbs H, Pratt AA, et al.. Risk of Delayed Intubation After Presumed Opioid Overdose in the Emergency Department
- Christenson J, Etherington J, Grafstein E, et al.. Early discharge of patients with presumed opioid overdose: development of a clinical prediction rule
- Willman MW, Liss DB, Schwarz ES, et al. Do heroin overdose patients require observation after receiving naloxone?