SSRI Toxicity Summary

Key Clinical Features

  • GI upset, tremor, agitation
  • Diaphoresis, dizziness, dilated pupils
  • Drowsiness, convulsions, coma
  • Tachycardia, QT/QRS prolongation
  • Rhabdomyolysis, hepatotoxicity

Serotonin Toxicity

  • CNS: Agitation, confusion, delirium
  • Autonomic: Tachycardia, fever, hypertension
  • Neuromuscular: Myoclonus, hyperreflexia
  • Severe: Convulsions, hyperthermia

Cardiac Monitoring

  • 12-lead ECG on arrival
  • Repeat ECGs in symptomatic patients
  • Monitor QRS and QT intervals
  • Check electrolytes (K+, Mg++, Ca++)
  • Risk of Torsade de Pointes

Emergency Management

  • Airway protection first
  • Activated charcoal if <1 hour
  • Benzodiazepines for agitation/seizures
  • Magnesium for Torsade de Pointes
  • Cooling for hyperthermia

Observation Period

  • Minimum 6 hours observation
  • Asymptomatic + normal ECG = discharge
  • Symptomatic = observe until resolved
  • Check U&Es, glucose, LFTs, CK

Specific Treatments

  • Serotonin toxicity: Benzodiazepines
  • Severe cases: Cyproheptadine
  • Hyperthermia: Active cooling
  • Rhabdomyolysis: IV fluids

Critical Investigations

  • ECG (serial)
  • Electrolytes
  • ABG for acidosis
  • CK for rhabdomyolysis
  • LFTs, glucose

Selective Serotonin Reuptake Inhibitor (SSRI) Toxicity

Comprehensive guide to clinical features, diagnosis, and management of SSRI overdose

Clinical Features

General Symptoms

  • GI upset
  • Tremor
  • Agitation
  • Diaphoresis
  • Dizziness
  • Dilated pupils
  • Drowsiness
  • Convulsions and coma

Cardiovascular Features

  • Tachycardia
  • Hypotension or hypertension
  • QT and QRS prolongation
  • Torsade de Pointes

Systemic Complications

  • Rhabdomyolysis (may occur without seizures)
  • Hepatotoxicity
  • Hypoglycemia

Serotonin Toxicity

Serotonin toxicity typically occurs when patients are exposed to two or more drugs that increase the effect of serotonin on serotonergic synapses.

Clinical Triad of Serotonin Toxicity

CNS Effects

  • Agitation
  • Confusion
  • Delirium
  • Hallucinations
  • Drowsiness and coma (severe cases)

Autonomic Instability

  • Tachycardia
  • Fever
  • Hypertension or hypotension
  • Flushing
  • Diarrhea and vomiting

Neuromuscular Excitability

  • Profound shivering
  • Tremor
  • Teeth grinding (bruxism)
  • Myoclonus
  • Hyperreflexia

Severe Complications

  • Convulsions
  • Hyperthermia
  • Rhabdomyolysis
  • Acute kidney injury
  • Coagulopathies
  • Multi-organ failure

Initial Management

Primary Survey & Stabilization
  1. Maintain a clear airway and ensure adequate ventilation
  2. Gastric decontamination: Consider activated charcoal (50g adults, 1g/kg children) if within 1 hour of ingestion and airway can be protected
  3. Cardiac monitoring: Perform 12-lead ECG in all patients

Note: Efficacy of activated charcoal declines rapidly with time but may have benefit with sustained-release preparations or large ingestions.

Cardiac Monitoring & Management

SSRIs are cardiotoxic and can cause QT prolongation and Torsade de Pointes.

ECG Monitoring Protocol

Electrolyte Management

Electrolyte Action
Potassium (K+) Keep within high normal range
Magnesium (Mg++) Replace as necessary
Calcium (Ca++) Replace as necessary

Torsade de Pointes Management

  • Torsade de Pointes and VT/VF preceded by prolonged QT should be treated urgently with magnesium sulphate
  • Consider magnesium sulphate when QT-heart rate nomogram indicates risk of Torsade de Pointes
  • Note: Magnesium sulphate may terminate Torsade de Pointes but does not shorten QT interval

Observation & Monitoring

Observation Period

  • All patients should be observed for at least 6 hours after ingestion
  • Patients who are asymptomatic at 6 hours, with normal heart rate and ECG, and no serotonergic features can be considered for discharge
  • Symptomatic patients should be observed until symptoms resolve

Laboratory Investigations

Symptomatic Patients

  • U&Es (renal function)
  • Glucose
  • LFTs (hepatotoxicity)
  • CK (rhabdomyolysis)

Additional Monitoring

  • ABG (acidosis correction)
  • Cardiac monitoring
  • Core temperature
  • Urine output (target ≥0.5 mL/kg/hour)

Specific Treatment Modalities

Agitation and Delirium

Management Approach
  1. Follow local guidelines for agitation/delirium
  2. Primary goal: Keep patient and staff safe while allowing continued evaluation
  3. De-escalation: Reduce environmental stimuli (quiet room)
  4. Provide basic needs: Close relative, warm blanket, food if appropriate

Serotonin Toxicity Treatment

Severity Treatment
Mild to Moderate Benzodiazepines (standard treatment)
Severe Cases Consider cyproheptadine and chlorpromazine (5HT2A antagonists)

Note: Most mild cases resolve spontaneously within 24 hours. No controlled trials support the use of cyproheptadine or chlorpromazine, though they have been used successfully.

Complication Management

Hyperthermia

Mild to Moderate (≤38°C)

  • Conventional cooling measures
  • Mist and fan techniques
  • Ice packs to groin and axillae
  • External cooling devices

Severe (>38°C or rising rapidly)

  • Urgent cooling measures
  • Regular core temperature monitoring
  • Ice-baths, cold fluid lavage
  • Intravascular cooling techniques
  • Rapid sequence intubation with paralysis
  • Neuromuscular paralysis + benzodiazepine infusion
  • Consider dantrolene for muscular hyperactivity

Convulsions

  • Single brief convulsions do not require treatment
  • Control frequent or prolonged convulsions with:
    • Intravenous diazepam
    • Lorazepam
    • Midazolam

Hypotension

  • Ensure adequate fluid resuscitation
  • Treat brady- and tachyarrhythmias appropriately
  • Consider early critical care referral for fluid-resistant hypotension
  • Vasopressors and inotropes can be initiated peripherally
  • WARNING: This should only be done under direction of experienced physician (SpR and above)

Rhabdomyolysis

  • Diagnosis: CK >5x upper limit of normal range
  • High risk: CK >5000 iu/L
  • Management:
    • IV volume replacement immediately
    • Maintain urine output ≥1ml/kg/h
    • Consider urine alkalinisation
    • Haemodialysis if acute renal failure develops
    • Haemodiafiltration for severe hyperkalaemia