T40

Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]

Category T40 represents a broad clinical classification for toxicological events involving narcotics (opioids) and psychodysleptics (hallucinogens). This category encompasses four distinct clinical scenarios: poisoning (accidental, intentional self-harm, assault, or undetermined intent), adverse effects (reactions to correctly administered therapeutic substances), underdosing (taking less of a medication than prescribed), and toxic effects of illicit substances. Opioid toxicity typically presents with a specific toxidrome involving central nervous system depression and respiratory insufficiency, while hallucinogen toxicity is characterized by significant perceptual distortions and autonomic instability. Clinicians must specify the intent and the encounter type (initial, subsequent, or sequela) using additional characters for definitive coding. This block is critical for monitoring public health trends in opioid crises and illicit drug use complications.

Clinical Symptoms

  • Respiratory depression (bradypnea or apnea)
  • Miosis (pinpoint pupils) - characteristic of opioid toxicity
  • Altered mental status ranging from lethargy to profound coma
  • Hypotension
  • Bradycardia
  • Cyanosis
  • Pulmonary edema (non-cardiogenic)
  • Hallucinations (visual, auditory, or tactile)
  • Mydriasis (dilated pupils) - common with certain psychodysleptics
  • Tachycardia and palpitations
  • Nystagmus
  • Psychosis or acute agitation
  • Flashbacks (hallucinogen persisting perception disorder)
  • Hyperreflexia
  • Seizures (particularly with certain synthetic narcotics)

Common Causes

  • Accidental overdose of prescribed opioid analgesics
  • Intentional self-poisoning (suicide attempts)
  • Illicit use of narcotics such as heroin or illicitly manufactured fentanyl
  • Recreational use of psychodysleptics (LSD, mescaline, psilocybin)
  • Adverse drug reactions to therapeutic doses of narcotics
  • Underdosing of medication due to patient non-compliance or financial barriers
  • Iatrogenic medication errors (wrong dose or wrong drug administration)
  • Inadvertent pediatric ingestion
  • Substance use disorder and physical dependence
  • Polysubstance use exacerbating narcotic effects

Documentation & Coding Tips

Distinguish between poisoning, adverse effect, and underdosing for all narcotics and psychodysleptics.

Example: Patient presented with obtundation and bradypnea. Investigation revealed the patient accidentally ingested double the prescribed dose of long-acting oxycodone for chronic lower back pain. Assessment: Accidental poisoning by other opioids (T40.2X1A). Billing Focus: Document as accidental intent. Risk Adjustment: Captures acute toxicity severity in HCC models.

Billing Focus: Identify the specific drug and the intent (accidental, intentional self-harm, assault, or undetermined).

Document clinical manifestations such as respiratory failure or coma as secondary codes.

Example: Patient seen in the emergency department for heroin poisoning. Patient found in coma with a Glasgow Coma Scale of 6 and acute respiratory failure. Documentation: Accidental heroin poisoning (T40.1X1A), Coma (R40.20), Acute respiratory failure with hypoxia (J96.01). Billing Focus: List T40.1X1A as the primary diagnosis. Risk Adjustment: Coma and respiratory failure are major comorbidities (MCC) that significantly increase the DRG weight.

Billing Focus: Include all associated symptoms as separate ICD-10 codes to support higher level E/M or inpatient DRG.

Verify the status of the encounter as initial, subsequent, or sequela.

Example: Patient presents for a follow-up visit after being discharged from the hospital for accidental fentanyl poisoning. Assessment: Poisoning by synthetic narcotics, accidental, subsequent encounter (T40.411D). Billing Focus: Use the 7th character D for subsequent care. Risk Adjustment: Subsequent encounters for poisoning do not carry the same HCC weight as initial encounters but are necessary for continuity of care records.

Billing Focus: 7th character A for active treatment; D for recovery/follow-up; S for late effects/sequela.

Identify specific agents within the psychodysleptics group such as LSD or cannabis.

Example: Patient admitted with acute psychosis and tachycardia after ingesting lysergide (LSD). Clinical note: Accidental poisoning by lysergides (T40.8X1A). Billing Focus: Specificity of the substance (LSD vs Cannabis vs Mescaline). Risk Adjustment: Substance-specific poisoning helps differentiate between toxicity-induced mental health symptoms and primary psychiatric disorders.

Billing Focus: Avoid using unspecified codes (T40.90) when the specific substance like LSD is known.

Clearly document if the condition is an adverse effect of a properly taken medication.

Example: Patient reports severe pruritus and nausea after taking methadone as prescribed for opioid maintenance therapy. Assessment: Adverse effect of methadone, initial encounter (T40.3X5A). Billing Focus: Adverse effect is used only when the drug was taken correctly. Risk Adjustment: Adverse effects differ from poisonings in clinical risk profiles and legal implications.

Billing Focus: Correctly use the 5th/6th character to denote adverse effect (5) versus poisoning (1-4).

Relevant CPT Codes

Related Diagnoses

Hierarchy