Overdoses of prescription meds may be unintentional

Med reconciliation reveals life-saving information

If your next patient had altered mental status and lethargy, would you suspect an unintentional overdose of pain medication?

Patients may not remember to remove transdermal pain patches when putting on a new one and suffer an unintentional overdose, says Karen Hust, RN-CEN, MSN, BSN, ADN, clinical educator for the ED at St. Joseph's/Candler Hospital in Savannah, GA.

When Hust was caring for an elderly woman with central nervous system (CNS) depression, a stroke protocol was initiated. "It wasn't until after CT [computerized tomography], when performing a skin assessment prior to admission, that we realized this patient was had four transdermal pain patches applied to her skin," says Hust. "The CT was negative, and the CNS problems resolved after removal of the patches."

Poisonings now are the second leading cause of unintentional injury death, with 20,950 deaths in 2004, according to the Centers for Disease Control and Prevention.1 Patients often accidentally take double doses of their medication, which can be life-threatening depending on the drug and dosage, says Scott Wiley, RN, of the Blue Ridge Poison Center in Charlottesville, VA. "If an elderly woman is on three different blood pressure medicines and takes both morning and evening doses, she has taken six doses, all of which can affect blood pressure," he notes. "Even fairly innocuous substances can be a problem in the right dose."

Signs that a patient's overdose of prescription opioid analgesics or sedatives could be life-threatening include abnormal vital signs, lethargy, unresponsiveness, and disorientation, says Michelle Langrehr, RN, MSN, FNP-C, an emergency nurse at St. Francis Hospital in Wilmington, DE. Ask these two questions at triage, she advises: Do you use any prescription pain medications? Do you use any street drugs or alcohol?

"It is not uncommon for patients, especially the elderly, to unintentionally overdose on their pain medication," says Hust. "This is why medication reconciliation is so valuable. Looking at the medications upon first contact provides a significant amount of information."

If you suspect an overdose of prescription medication, assess for the following, says Hust:

  • Hypotension and bradycardia.
  • Respiratory rate and effort. "Hypoxic drive may be overridden," says Hust.
  • Hypoxemia.
  • Signs and symptoms of noncardiogenic pulmonary edema: dyspnea, cough, frothy sputum, rales, and rhonchi.
  • CNS depression related to hypoxia and respiratory depression. "Seizures are common," says Hust. "Patients that have taken barbiturates may present initially as euphoric and decline from mild sedation to coma and death."
  • Slurred speech; miosis; nystagmus; emotional lability; and impaired memory, judgment, and attention.
  • Hypoglycemia, nausea and vomiting, decreased gastrointestinal motility, and urinary retention.
  • Pruritus, flushing, and urticaria.
  • Neuromuscular changes such as involuntary muscle twitching, hypoactive reflexes, flaccidity, or unsteady gait.

Regardless of the toxic agent, airway, breathing and circulation are always your highest priority, says Hust. Bedside glucose should be done rapidly, she says. "Accurate vital signs should be obtained frequently and trended, including pulse oximetry and at least one measurement of temperature," Hust says. "Rhythm strips should be reviewed and placed on the chart."

Identify the drug causing the symptoms as early as possible, before the patient loses the ability to communicate or family members leave your ED, says Hust. "Obtain all prescription information, including pill counts and identification of unknown pills," she says. "Search all patient belongings for clues to the causative agent."

Consider oral medication

For patients with potentially toxic acetaminophen, treatment with oral N-acetylcysteine (NAC) for 20-48 hours is safe and effective, says a new study.2 Of 195 patients contacted by researchers who were treated with NAC for 48 hours or less, 96% reported no symptoms consistent with hepatic failure.

"While the use of [intravenous] IV NAC is increasing, there's an increasing body of evidence that oral NAC given for shorter durations than the traditional 72 hours of treatment may be just as effective in a subset of acetaminophen-poisoned patients," says the study's author, David Betten, MD, assistant clinical professor in the Department of Emergency Medicine at Michigan State University College of Human Medicine in East Lansing.

ED nurses should consider oral NAC in patients especially for patients with underlying respiratory disease, since anaphylactoid reactions are much more common with IV NAC in these patients, says Betten. "Oral NAC is extremely safe, and with predosing with antiemetics, [it] is usually well tolerated."


  1. Paulozzi L. Unintentional poisoning deaths — United States, 1999-2004. MMWR 2007; 56:93-96.
  2. Betten DP, Cantrell FL, Thomas SC, et al. A prospective evaluation of shortened course oral N-acetylcysteine for the treatment of acute acetaminophen poisoning. Ann Emerg Med 2007; 50:272-279.


For more information on ED patients with unintentional overdoses, contact:

  • David P. Betten, MD, Assistant Clinical Professor, Department of Emergency Medicine, Sparrow Hospital, Lansing, MI. Phone: (517) 364-4120. Fax: (517) 364-3725. E-mail: bettend@msu.edu.
  • Karen Hust, RN-CEN, MSN, BSN, ADN, Advanced Clinical Educator, Emergency Department, St. Joseph's/Candler, Savannah, GA. Phone: (912) 819-6267. Fax: (912) 691-9224. E-mail: hustk@sjchs.org.
  • Michelle Langrehr, RN, MSN, CRNP, Emergency Department, St. Francis Hospital, Wilmington, DE. Phone: (302) 421-4343. E-mail: mblangrehr@comcast.net.