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Sympathomimetic poisoning is caused by excessive stimulation of adrenergic receptors in the central and peripheral nervous systems, either through direct receptor activation or indirect mechanisms such as increased catecholamine release. The severity of toxicity does not always correlate with the amount ingested. Certain substances, particularly cocaine, can also block sodium channels in cardiac myocytes, leading to dysrhythmias similar to those seen in tricyclic antidepressant toxicity.
Sympathomimetic toxicity can result from exposure to a wide variety of substances, including amphetamines, methamphetamines, MDMA (ecstasy), cocaine, synthetic cathinones (“bath salts”), phencyclidine (PCP), lysergic acid diethylamide (LSD), and occasionally decongestants. These substances may be administered via inhalation, injection, ingestion, or insufflation. In pediatric patients, presentation may mimic serious systemic illness such as meningitis, and diagnosis may only become apparent through toxicology screening. Medications used for attention deficit hyperactivity disorder, such as methylphenidate, may also contribute to this toxidrome.
Patients with sympathomimetic poisoning typically present with a recognizable toxidrome characterized by tachycardia, hypertension, tachypnea, and hyperthermia, although late hypotension may occur in severe cases. Neurologic manifestations include agitation, anxiety, altered mental status, seizures, and headache, while cardiovascular effects include palpitations, chest pain, myocardial ischemia, and tachydysrhythmias. Additional findings commonly include diaphoresis, which helps distinguish this condition from anticholinergic toxicity, as well as mydriasis and possible urinary retention. In severe toxicity, patients may develop agitated delirium, profound hyperthermia, seizures, and cardiovascular collapse.
Evaluation focuses on rapid assessment and monitoring for complications. Continuous monitoring of vital signs is essential, particularly core temperature due to the risk of life-threatening hyperthermia. An electrocardiogram should be obtained to assess for ischemia and arrhythmias. Laboratory investigations typically include electrolytes, renal function, glucose, creatine kinase to evaluate for rhabdomyolysis, and coagulation studies. Urine toxicology screening may be useful, although some substances may not be detected. Imaging such as CT of the brain may be indicated in patients with altered mental status or focal neurologic deficits. Careful assessment for associated trauma, infection, pneumothorax, or end-organ injury is also important.
Management begins with standard resuscitation principles, including ensuring airway, breathing, and circulation, establishing intravenous access, and initiating cardiac monitoring. In patients with altered mental status, administration of dextrose, naloxone, and thiamine should be considered. The cornerstone of treatment is sedation with benzodiazepines, which effectively reduce agitation, hypertension, and seizure risk. Hyperthermia must be treated aggressively with sedation and active cooling measures such as evaporative cooling, and paralysis may be required in refractory cases. Hypertension is initially managed with benzodiazepines, followed by vasodilators such as nicardipine or nitroglycerin if necessary, while β-blockers should be avoided due to the risk of unopposed α-adrenergic activity. Dysrhythmias associated with sodium channel blockade are treated with sodium bicarbonate, and lidocaine may be used if refractory. Seizures are treated with benzodiazepines, with phenobarbital as second-line therapy. Rhabdomyolysis requires aggressive intravenous fluid resuscitation to maintain adequate urine output, and dialysis may be necessary if renal failure or severe hyperkalemia develops. Decontamination has a limited role and is generally reserved for selected cases such as early ingestion or body packers.
Patients with severe manifestations such as seizures, dysrhythmias, hyperthermia, rhabdomyolysis, altered mental status, or significant hypertension should be admitted to a monitored setting. Mildly intoxicated patients who improve with treatment may be observed in the emergency department until symptoms resolve and then discharged safely. Referral for substance use treatment and rehabilitation should be considered when appropriate.
Benzodiazepines remain the first-line therapy for most manifestations of sympathomimetic poisoning and should be administered early. Hyperthermia above 40°C is a critical, life-threatening condition requiring immediate intervention. β-blockers should be avoided because they may worsen hypertension through unopposed α-adrenergic stimulation. Early recognition and management of complications such as rhabdomyolysis and hyperkalemia are essential to prevent morbidity and mortality. Clinicians must also remain vigilant for concurrent emergencies, including acute coronary syndrome, trauma, and infection, which may coexist in these patients.
Sympathomimetic toxicity can result from exposure to a wide variety of substances, including amphetamines, methamphetamines, MDMA (ecstasy), cocaine, synthetic cathinones (“bath salts”), phencyclidine (PCP), lysergic acid diethylamide (LSD), and occasionally decongestants. These substances may be administered via inhalation, injection, ingestion, or insufflation. In pediatric patients, presentation may mimic serious systemic illness such as meningitis, and diagnosis may only become apparent through toxicology screening. Medications used for attention deficit hyperactivity disorder, such as methylphenidate, may also contribute to this toxidrome.
Patients with sympathomimetic poisoning typically present with a recognizable toxidrome characterized by tachycardia, hypertension, tachypnea, and hyperthermia, although late hypotension may occur in severe cases. Neurologic manifestations include agitation, anxiety, altered mental status, seizures, and headache, while cardiovascular effects include palpitations, chest pain, myocardial ischemia, and tachydysrhythmias. Additional findings commonly include diaphoresis, which helps distinguish this condition from anticholinergic toxicity, as well as mydriasis and possible urinary retention. In severe toxicity, patients may develop agitated delirium, profound hyperthermia, seizures, and cardiovascular collapse.
Evaluation focuses on rapid assessment and monitoring for complications. Continuous monitoring of vital signs is essential, particularly core temperature due to the risk of life-threatening hyperthermia. An electrocardiogram should be obtained to assess for ischemia and arrhythmias. Laboratory investigations typically include electrolytes, renal function, glucose, creatine kinase to evaluate for rhabdomyolysis, and coagulation studies. Urine toxicology screening may be useful, although some substances may not be detected. Imaging such as CT of the brain may be indicated in patients with altered mental status or focal neurologic deficits. Careful assessment for associated trauma, infection, pneumothorax, or end-organ injury is also important.
Management begins with standard resuscitation principles, including ensuring airway, breathing, and circulation, establishing intravenous access, and initiating cardiac monitoring. In patients with altered mental status, administration of dextrose, naloxone, and thiamine should be considered. The cornerstone of treatment is sedation with benzodiazepines, which effectively reduce agitation, hypertension, and seizure risk. Hyperthermia must be treated aggressively with sedation and active cooling measures such as evaporative cooling, and paralysis may be required in refractory cases. Hypertension is initially managed with benzodiazepines, followed by vasodilators such as nicardipine or nitroglycerin if necessary, while β-blockers should be avoided due to the risk of unopposed α-adrenergic activity. Dysrhythmias associated with sodium channel blockade are treated with sodium bicarbonate, and lidocaine may be used if refractory. Seizures are treated with benzodiazepines, with phenobarbital as second-line therapy. Rhabdomyolysis requires aggressive intravenous fluid resuscitation to maintain adequate urine output, and dialysis may be necessary if renal failure or severe hyperkalemia develops. Decontamination has a limited role and is generally reserved for selected cases such as early ingestion or body packers.
Patients with severe manifestations such as seizures, dysrhythmias, hyperthermia, rhabdomyolysis, altered mental status, or significant hypertension should be admitted to a monitored setting. Mildly intoxicated patients who improve with treatment may be observed in the emergency department until symptoms resolve and then discharged safely. Referral for substance use treatment and rehabilitation should be considered when appropriate.
Benzodiazepines remain the first-line therapy for most manifestations of sympathomimetic poisoning and should be administered early. Hyperthermia above 40°C is a critical, life-threatening condition requiring immediate intervention. β-blockers should be avoided because they may worsen hypertension through unopposed α-adrenergic stimulation. Early recognition and management of complications such as rhabdomyolysis and hyperkalemia are essential to prevent morbidity and mortality. Clinicians must also remain vigilant for concurrent emergencies, including acute coronary syndrome, trauma, and infection, which may coexist in these patients.
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