Overdose

Specialties > Child health

Differential Diagnosis Schema 🧠

Common Overdoses

Paracetamol: common in deliberate self-harm; may present with nausea, vomiting, right upper quadrant pain, and elevated liver enzymes
Opiates: respiratory depression, pinpoint pupils, reduced consciousness, and risk of aspiration pneumonia
Benzodiazepines: drowsiness, ataxia, respiratory depression (especially when combined with other CNS depressants)
Tricyclic antidepressants: anticholinergic effects (dry mouth, blurred vision, urinary retention), arrhythmias, seizures, coma
Salicylates: tinnitus, hyperventilation, metabolic acidosis, and risk of cerebral edema
Alcohol: CNS depression, hypoglycemia, metabolic acidosis, hypothermia

Less Common Overdoses

Iron: gastrointestinal symptoms (vomiting, diarrhea), metabolic acidosis, hepatotoxicity, shock
Lithium: tremor, hyperreflexia, ataxia, seizures, nephrotoxicity, thyroid dysfunction
Theophylline: tachycardia, tremor, vomiting, hypokalemia, seizures
Calcium channel blockers: hypotension, bradycardia, hyperglycemia
Beta-blockers: bradycardia, hypotension, hypoglycemia, bronchospasm
Digoxin: nausea, vomiting, bradycardia, visual disturbances (yellow/green halos), arrhythmias
Organophosphates: salivation, lacrimation, urination, defecation, gastrointestinal upset, miosis (SLUDGE symptoms)

Environmental and Recreational Toxins

Carbon monoxide: headache, dizziness, cherry-red skin, altered mental state, metabolic acidosis
Recreational drugs (e.g., MDMA, cocaine): agitation, hyperthermia, arrhythmias, seizures, rhabdomyolysis
Methanol: visual disturbances, metabolic acidosis, CNS depression
Ethylene glycol: metabolic acidosis, renal failure, CNS depression, oxalate crystals in urine

Key Points in History 🥼

Presenting Symptoms

Time of ingestion: provides information on potential time to onset of symptoms and urgency of treatment
Quantity ingested: helps estimate the severity of overdose and guide management
Intent: differentiate between accidental, deliberate self-harm, or recreational use
Co-ingestants: identify additional substances taken, especially those that may exacerbate toxicity (e.g., alcohol with benzodiazepines)
Symptoms: nausea, vomiting, abdominal pain, confusion, drowsiness, seizures

Background

Past Medical History: history of depression, substance abuse, chronic pain, or previous overdoses
Drug History: prescribed medications, over-the-counter drugs, herbal remedies, and illicit substances
Family History: familial predisposition to mental health disorders or substance abuse
Social History: recent life stressors, social isolation, financial difficulties, employment status
Alcohol and Recreational Drug Use: chronic use, recent binge, or withdrawal states
Access to Toxins: access to large quantities of medications, chemicals, or other toxic substances

Possible Investigations 🌡️

Blood Tests

Full Blood Count (FBC): assess for anemia, infection, or platelet abnormalities
Urea and Electrolytes (U&E): monitor renal function, electrolyte imbalances, and dehydration
Liver Function Tests (LFTs): assess for hepatotoxicity, particularly in paracetamol overdose
Arterial Blood Gas (ABG): detect metabolic acidosis, especially in salicylate, methanol, or ethylene glycol toxicity
Serum drug levels: measure specific levels (e.g., paracetamol, salicylate, lithium, digoxin) for targeted management
Coagulation profile: monitor in cases of hepatotoxicity or significant bleeding risk
Blood glucose: monitor for hypoglycemia, particularly in alcohol or insulin overdoses
Toxicology screen: identify the presence of multiple toxins, though not always routinely available or necessary

Imaging and Monitoring

ECG: essential for detecting arrhythmias, particularly in tricyclic antidepressant, beta-blocker, or digoxin toxicity
Chest X-ray: assess for aspiration pneumonia or pulmonary edema in patients with decreased consciousness
CT Head: indicated if there is concern for cerebral edema, especially in salicylate or severe carbon monoxide poisoning
Continuous monitoring: vital signs, oxygen saturation, urine output, and cardiac monitoring in severe cases

Specialist Tests

Paracetamol nomogram: guides treatment based on time since ingestion and serum levels
Ethanol level: particularly in suspected alcohol poisoning or to differentiate from other alcohols (e.g., methanol)
Iron levels: relevant in suspected iron overdose; levels correlate with toxicity risk
Lactate: elevated in severe sepsis, shock, or cyanide toxicity

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