Poisoning is the leading cause of injury-related morbidity and mortality in the United States. The highest rates of exposure to poisons occur in children five years and younger, but opioid overdoses in young adults account for most deaths from poisonings in recent years. Intentional or accidental medication poisoning should be considered when evaluating patients with mental status changes, vital sign abnormalities, seizures, and gastrointestinal or cardiovascular problems. For all poisoned patients, a comprehensive history and physical examination are needed. Knowledge of toxidromes may help identify the cause in unknown ingestions; however, their usefulness may be limited when multiple toxins are ingested. Electrocardiography is indicated in patients reporting chest pain and dyspnea and in overdoses of beta blockers, tricyclic antidepressants, and antidysrhythmics. Measurement of electrolyte, serum creatinine, and serum bicarbonate levels and calculation of the anion gap may be helpful based on the clinical presentation. Treatment of a patient with acute poisoning is based on resuscitation and stabilization with a focus on airway, breathing, and circulation. When poisoning is suspected, the Poison Control provides health care workers and the public with access to a specialist 24 hours a day.