All EMS presentations
ToxicologyClinical presentation

Overdose / drug poisoning

A streamlined, differential-led presentation for rapid clinical review.

Clinical snapshot

Twenty-second review

  • Drug poisoning may depress or stimulate the nervous system, impair ventilation, alter conduction, disrupt temperature control, or cause delayed organ injury.
  • Bradypnea, apnea, shock, seizure, dysrhythmia, hyperthermia, severe agitation, or declining GCS requires immediate supportive care and escalation.
  • Keep hypoglycemia or head injury in the differential; overlapping or concurrent illness remains possible.
  • For overdose / drug poisoning, trends and combinations of findings are more informative than one isolated vital sign.
Differentials

Compare the clinical patterns

The repeated material is grouped inside each possibility. Open only the condition you need.

Serious2 conditions
CardiotoxicTime-sensitive high-risk possibility

HPI

Clarify substance(s), amount, route and time; intentional or accidental; co-ingestants.

Signs & symptoms

QRS or QT change, hypotension, seizure, or dysrhythmia.

Focused exam

Assess pupils, skin, bowel sounds, temperature, mental status, respiratory pattern, rhythm, and signs of trauma or concealed co-ingestion; Repeat observations because drug effects may evolve.

Brief pathophysiology

Cardiotoxic may cause overdose / drug poisoning through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Toxic effects vary by agent and co-exposure. Ventilation, rate/rhythm, pressure, and temperature are the most useful four observations for recognizing an evolving toxidrome.

Respiratory rate (breaths/min)

May rise or fall

Ventilation can be depressed or stimulated depending on the agent.

Heart rate (bpm)

Rate / rhythm may change

Obtain ECG monitoring when cardiotoxicity is plausible.

Blood pressure (mmHg)

May rise or fall

Pressure direction depends on agent, dose, and stage.

Temperature (°C)

May rise or fall

Temperature disturbance can identify severe stimulant, anticholinergic, sedative, or environmental toxicity.

Front-load in the triage report

  • Cardiotoxic: QRS or QT change, hypotension, seizure, or dysrhythmia.
  • Substance(s), amount, route and time.
  • Intentional or accidental?
Mixed overdoseTime-sensitive high-risk possibility

HPI

Clarify intentional or accidental; co-ingestants; initial loc, rr and spo2.

Signs & symptoms

QRS or QT change, hypotension, seizure, or dysrhythmia.

Focused exam

Repeat observations because drug effects may evolve; Assess pupils, ventilation, skin, temperature, rhythm, trauma, injection sites, pill containers, and co-ingestants.

Brief pathophysiology

Mixed overdose may cause overdose / drug poisoning through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Toxic effects vary by agent and co-exposure. Ventilation, rate/rhythm, pressure, and temperature are the most useful four observations for recognizing an evolving toxidrome.

Respiratory rate (breaths/min)

May rise or fall

Ventilation can be depressed or stimulated depending on the agent.

Heart rate (bpm)

Rate / rhythm may change

Obtain ECG monitoring when cardiotoxicity is plausible.

Blood pressure (mmHg)

May rise or fall

Pressure direction depends on agent, dose, and stage.

Temperature (°C)

May rise or fall

Temperature disturbance can identify severe stimulant, anticholinergic, sedative, or environmental toxicity.

Front-load in the triage report

  • Mixed overdose: QRS or QT change, hypotension, seizure, or dysrhythmia.
  • Intentional or accidental?
  • Co-ingestants.
Common2 conditions
SedativeCommon presentation pattern

HPI

Clarify substance(s), amount, route and time; intentional or accidental; co-ingestants.

Signs & symptoms

Reduced consciousness, bradypnea, shallow breathing, or miosis may predominate.

Focused exam

Assess pupils, skin, bowel sounds, temperature, mental status, respiratory pattern, rhythm, and signs of trauma or concealed co-ingestion; Repeat observations because drug effects may evolve.

Brief pathophysiology

Sedative may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Ventilation is the priority in opioid or sedative toxicity. SpO₂ can look acceptable with supplemental oxygen while dangerous hypoventilation persists.

Respiratory rate (breaths/min)

May fall

Bradypnea, shallow breathing, or apnea indicates ventilatory failure.

Oxygen saturation (SpO₂)

May fall

Desaturation can occur, but SpO₂ does not measure ventilation.

Heart rate (bpm)

Variable

Rate depends on agent, co-ingestants, hypoxia, and baseline.

Blood pressure (mmHg)

May fall

Hypotension can occur in severe toxicity or mixed overdose.

Front-load in the triage report

  • Reduced consciousness, bradypnea, shallow breathing, or miosis may predominate.
  • Substance(s), amount, route and time.
  • Intentional or accidental?
Opioid toxicityCommon presentation pattern

HPI

Clarify intentional or accidental; co-ingestants; initial loc, rr and spo2.

Signs & symptoms

Reduced consciousness, bradypnea, shallow breathing, or miosis may predominate.

Focused exam

Repeat observations because drug effects may evolve; Assess pupils, ventilation, skin, temperature, rhythm, trauma, injection sites, pill containers, and co-ingestants.

Brief pathophysiology

Opioid toxicity may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Ventilation is the priority in opioid or sedative toxicity. SpO₂ can look acceptable with supplemental oxygen while dangerous hypoventilation persists.

Respiratory rate (breaths/min)

May fall

Bradypnea, shallow breathing, or apnea indicates ventilatory failure.

Oxygen saturation (SpO₂)

May fall

Desaturation can occur, but SpO₂ does not measure ventilation.

Heart rate (bpm)

Variable

Rate depends on agent, co-ingestants, hypoxia, and baseline.

Blood pressure (mmHg)

May fall

Hypotension can occur in severe toxicity or mixed overdose.

Front-load in the triage report

  • Reduced consciousness, bradypnea, shallow breathing, or miosis may predominate.
  • Intentional or accidental?
  • Co-ingestants.
Mimics2 conditions
HypoglycemiaImportant alternative presentation

HPI

Clarify substance(s), amount, route and time; intentional or accidental; co-ingestants.

Signs & symptoms

Common reversible or traumatic mimics of intoxication.

Focused exam

Assess pupils, skin, bowel sounds, temperature, mental status, respiratory pattern, rhythm, and signs of trauma or concealed co-ingestion; Repeat observations because drug effects may evolve.

Brief pathophysiology

Hypoglycemia can resemble overdose / drug poisoning through overlapping symptoms or referred physiology despite a different primary mechanism.

Vital-sign pattern

What the trend may show

Possible pattern

Confirm low capillary glucose and reassess after treatment. Adrenergic signs may be absent in recurrent hypoglycemia or blunted by medications.

Blood glucose (mmol/L)

< 4.0 mmol/L

BCEHS defines hypoglycemia as blood glucose below 4.0 mmol/L.

Heart rate (bpm)

May rise

Adrenergic activation commonly produces tachycardia, but this is not universal.

Blood pressure (mmHg)

Often preserved

Blood pressure is not a reliable discriminator; hypotension suggests another or additional process.

Temperature (°C)

May fall

Hypothermia can accompany prolonged or severe hypoglycemia.

Front-load in the triage report

  • Common reversible or traumatic mimics of intoxication.
  • Substance(s), amount, route and time.
  • Intentional or accidental?
Head injuryImportant alternative presentation

HPI

Clarify intentional or accidental; co-ingestants; initial loc, rr and spo2.

Signs & symptoms

Common reversible or traumatic mimics of intoxication.

Focused exam

Repeat observations because drug effects may evolve; Assess pupils, ventilation, skin, temperature, rhythm, trauma, injection sites, pill containers, and co-ingestants.

Brief pathophysiology

Head injury can resemble overdose / drug poisoning through overlapping symptoms or referred physiology despite a different primary mechanism.

Vital-sign pattern

What the trend may show

Possible pattern

Toxic effects vary by agent and co-exposure. Ventilation, rate/rhythm, pressure, and temperature are the most useful four observations for recognizing an evolving toxidrome.

Respiratory rate (breaths/min)

May rise or fall

Ventilation can be depressed or stimulated depending on the agent.

Heart rate (bpm)

Rate / rhythm may change

Obtain ECG monitoring when cardiotoxicity is plausible.

Blood pressure (mmHg)

May rise or fall

Pressure direction depends on agent, dose, and stage.

Temperature (°C)

May rise or fall

Temperature disturbance can identify severe stimulant, anticholinergic, sedative, or environmental toxicity.

Front-load in the triage report

  • Common reversible or traumatic mimics of intoxication.
  • Intentional or accidental?
  • Co-ingestants.
Red flags

Findings that should escalate concern

  • Bradypnea, apnea, shock, seizure, dysrhythmia, hyperthermia, severe agitation, or declining GCS requires immediate supportive care and escalation.
  • Cardiotoxic or mixed overdose: QRS or QT change, hypotension, seizure, or dysrhythmia.
Related medications

Medication recognition

HydromorphoneOxycodoneMethadoneNaloxone
Related EMS presentations

Continue the clinical pathway

NeurologicAltered LOC / confusionToxicologyAlcohol intoxicationToxicologyPoisoning / toxic exposureToxicologyOpioid withdrawalToxicologyStimulant toxicity
References

Clinical and academic sources

Curated clinical guidance and peer-reviewed evidence supporting this presentation. Current BCEHS guidance, medical direction, and local policy remain authoritative for practice.

BCEHS Handbook — specific CPGs

  1. J01: Approach to Chemical or Toxic ExposuresBC Emergency Health Services Handbook

    Official BCEHS clinical practice guidance for approach to chemical or toxic exposures.

Supporting clinical and academic evidence

  1. CEDIS Presenting Complaint List updateCanadian Association of Emergency Physicians

    Presenting-complaint terminology and categorization context. It does not establish a prehospital “top 100” ranking.

  2. Guidelines for establishing a poison centreWorld Health Organization

    Clinical toxicology context for time-critical poisoning, supportive care, consultation, and poison-centre expertise.

  3. Adult and Pediatric Special Circumstances of Resuscitation: 2025 AHA GuidelinesCirculation · 2025

    Evidence-based resuscitation considerations for poisoning and other reversible special circumstances.