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tox.acetaminophen-overdose.core.v1PRODUCTION
tox.acetaminophen-overdose.core.v1
Acetaminophen (paracetamol) overdose
toxicologyacuteadultpediatricpregnancy
Hard-required inputs
0 / 13
Care setting:
Encounter flow
12/12 authoredCanonical 12-phase frame with authored status for this dossier.
Current phase
Frame
Confirm acute APAP toxicity scope; route massive/late presenters to transplant pathway
Inputs
2
Actions
0
Advance rule
Set
Advance when
Acute APAP overdose confirmed; massive/late triggers flagged
Patient inputs (19)
Pediatric and adult NAC weight bands; pediatric dilution rules (<20 kg)
NAC dosing is mg/kg with 110 kg cap
Nomogram applicability (4–24 h); empiric NAC if >8 h or unknown
Massive ingestion (>30 g) flag; staggered vs single decision
Nomogram does not apply when staggered or time unclear
Plotted on Rumack-Matthew nomogram for treatment-line decision
ALT >1000 = hepatotoxicity; trends drive NAC continuation
INR rising after 24 h → ongoing injury; KCC component
KCC criterion (Cr >300) and AKI co-morbidity
KCC arterial pH <7.3 single criterion → transplant referral
Lactate >3.5 mmol/L early predictor of poor outcome
Hypoglycemia common in hepatotoxicity; D10 infusion trigger
Mandatory co-ingestion screen
CYP2E1 induction + GSH depletion lowers toxic threshold
INH/rifampin/phenytoin/carbamazepine increase NAPQI
NAC is safe in pregnancy; MFM/fetal monitoring required
Anaphylactoid reaction history changes infusion approach
Glutathione depletion + sedation modifier
Grade III/IV encephalopathy is a KCC criterion + intubation trigger
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Severity triggers (7)
7 need judgement
- informationallife_threateningkcc_arterial_ph_under_7_3Arterial pH <7.3 after fluid resuscitation (KCC single-criterion threshold) — O'Grady 1989 KCCTrigger could not be auto-evaluated — needs clinician judgement.
- informationallife_threateningkcc_triple_criterionINR >6.5 (PT >100s) AND creatinine >300 µmol/L AND grade III/IV HE — O'Grady 1989 KCCTrigger could not be auto-evaluated — needs clinician judgement.
- informationalsevereabove_rumack_matthew_line4-h+ APAP level above the 150 mg/L (US) / 100 mg/L (UK) treatment line on Rumack-Matthew nomogram — Rumack-Matthew 1975Trigger could not be auto-evaluated — needs clinician judgement.
- informationalseverelate_presentation_or_staggeredTime since ingestion >8 h, unknown timing, or staggered ingestion — nomogram does not apply — ACMT 2023Trigger could not be auto-evaluated — needs clinician judgement.
- informationalseverelactate_high_post_resusLactate >3.5 mmol/L after fluid resuscitation (refined KCC) — Bernal 2002Trigger could not be auto-evaluated — needs clinician judgement.
- informationalseveremassive_ingestion_over_30gReported ingestion >30 g (or >500 mg/kg in pediatric) — NICE 2024Trigger could not be auto-evaluated — needs clinician judgement.
- informationalseverepregnancy_apap_overdosePregnant patient with APAP overdose at any level above treatment line or with unknown timing — Heard NEJM 2008Trigger could not be auto-evaluated — needs clinician judgement.
Workflow calculators
Run this disease's risk and dosing calculators inline.
RISK_STRATIFICATIONoptionalDrives risk stratification
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Recommended regimen
APAP antidote — N-acetylcysteine (Prescott IV 21-h vs PO 72-h)axis: apap_antidotestep 1 - IV NAC 21-h Prescott — load
Selected step "IV NAC 21-h Prescott — load" — Above Rumack-Matthew treatment line at 4-24 h, OR staggered ingestion, OR unknown time, OR late presenter (>8 h) awaiting level
- acetylcysteinefirst lineantidote_glutathione_precursor150 mg/kg (max 110 kg → 16,500 mg) • IV • over 60 minutes (Prescott load) (max: 16,500 mg load (110 kg cap))triggers: above_rumack_matthew_line, staggered_or_unknown_time, empiric_if_gt_8h_awaiting_levelPrescott regimen — Prescott Lancet 1979; modified to 60-min infusion (originally 15 min) to reduce anaphylactoid reactionsrxcui 197
ed playbook — drug actions (5)
- 1. activated_charcoalrxcui 2721 g/kg PO/NG • PO • singletrigger: Within 1-2 h ingestion + airway protected + cooperativeGI decontamination window
- 2. acetylcysteine_loadrxcui 197150 mg/kg • IV over 60 min • loadtrigger: Above Rumack-Matthew line OR >8 h with unknown level OR staggered/unknown timePrescott load — start within 8 h ideal
- 3. acetylcysteine_bag2rxcui 19750 mg/kg • IV over 4 h • after loadtrigger: Load completeBag 2 of 21-h Prescott
- 4. acetylcysteine_bag3rxcui 197100 mg/kg • IV over 16 h • after bag 2trigger: Bag 2 completeBag 3 — total 300 mg/kg over 21 h
- 5. dextrose_50rxcui 485025-50 g IV • IV • PRN + D10 driptrigger: Hypoglycemia (especially in ALF)Glucose <70 — start D10 drip
Auto-drafted A&P note
edSubjective
- Possible entry pathways: Reported ingestion of acetaminophen / paracetamol; Detectable serum acetaminophen level; Unexplained ALT elevation in poly-substance/intentional ingestion.
Objective
- No vitals, labs, or imaging entered for this encounter.
Assessment
**Acetaminophen (paracetamol) overdose** (tox.acetaminophen-overdose.core.v1). Phenotype framing: Rule out viral hepatitis, ischemic hepatitis, alcoholic hepatitis, mushroom (Amanita), Wilson, autoimmune, AFLP/HELLP if pregnant, salicylate co-ingestion Scope: Confirm acute APAP toxicity scope; route massive/late presenters to transplant pathway No severity triggers fired against current inputs.
Plan
Regimen axis: **APAP antidote — N-acetylcysteine (Prescott IV 21-h vs PO 72-h)** — step "IV NAC 21-h Prescott — load". 1. acetylcysteine 150 mg/kg (max 110 kg → 16,500 mg) IV over 60 minutes (Prescott load) (antidote_glutathione_precursor, first line) — Prescott regimen — Prescott Lancet 1979; modified to 60-min infusion (originally 15 min) to reduce anaphylactoid reactions Setting playbook (ed) — Risk-stratify ingestion, decide NAC vs observation by 4-h+ APAP and Rumack-Matthew, start NAC empirically if late or staggered 2. activated_charcoal 1 g/kg PO/NG PO single — Within 1-2 h ingestion + airway protected + cooperative (GI decontamination window) 3. acetylcysteine_load 150 mg/kg IV over 60 min load — Above Rumack-Matthew line OR >8 h with unknown level OR staggered/unknown time (Prescott load — start within 8 h ideal) 4. acetylcysteine_bag2 50 mg/kg IV over 4 h after load — Load complete (Bag 2 of 21-h Prescott) 5. acetylcysteine_bag3 100 mg/kg IV over 16 h after bag 2 — Bag 2 complete (Bag 3 — total 300 mg/kg over 21 h) 6. dextrose_50 25-50 g IV IV PRN + D10 drip — Hypoglycemia (especially in ALF) (Glucose <70 — start D10 drip) Non-pharmacologic actions: - IV access x 2 large-bore — NICE 2024 - Continuous cardiac + SpO2 monitoring — NICE 2024 - NPO if encephalopathic — AASLD 2023 (Stravitz) - Psych evaluation if intentional — NICE 2024 - Notify regional poison center / toxicology consult — NICE 2024 - Transfer to transplant centre if any KCC criterion met — O'Grady 1989 KCC AVOID / contraindication checks: - Nac anaphylactoid reaction mgmt on prior history — Heard NEJM 2008 - Slow_NAC_load_to_60_min_to_reduce_anaphylactoid — Prescott Lancet 1979; NICE 2024 - Vit_K_only_if_bleeding_avoid_blunting_KCC_marker — AASLD 2023 (Stravitz)
Monitoring
Regimen monitoring: - NAC reaction watch first hour — Heard NEJM 2008 - LFTs q12h during treatment — AASLD 2023 (Stravitz) - INR q6 12h until trending — AASLD 2023 (Stravitz) - creatinine q12h for KCC — O'Grady 1989 KCC - arterial pH q4-6h — O'Grady 1989 KCC - lactate q4-6h — Bernal 2002 - glucose q4-6h — AASLD 2023 (Stravitz) - west haven grade q4h — AASLD 2023 (Stravitz) - repeat apap at end of nac — ACMT 2023 Setting (ed) monitoring: - APAP / ALT / INR / creatinine / glucose / lactate / ABG q6h initially — AASLD 2023 (Stravitz) - West Haven grade q4h — AASLD 2023 (Stravitz) - Continuous telemetry + SpO2 — NICE 2024 - NAC infusion reaction watch — first 60 min and ongoing — Heard NEJM 2008 Follow-up plan: Psychiatry safety plan, hepatology if injury, PCP med review, social work, poison-prevention education, child protection if pediatric - Close-out criterion: Discharge plan + safety plan documented Monitoring phase: Serial LFTs q12h, INR q6–12h, Cr q12h, glucose q4–6h, lactate/pH q4–6h, West Haven q4h, repeat APAP at end of NAC, NAC reaction watch first hour
Disposition
Current setting: ed — Risk-stratify ingestion, decide NAC vs observation by 4-h+ APAP and Rumack-Matthew, start NAC empirically if late or staggered Disposition criteria: - Discharge home: 4-h+ APAP undetectable AND below Rumack-Matthew line AND no NAC indication AND no co-ingestants AND psych cleared — Rumack-Matthew 1975; NICE 2024 - Admit ward: NAC running, ALT normal, INR <2, no encephalopathy — ACMT 2023 - Admit ICU: any KCC criterion met, grade III/IV HE, pH <7.3, lactate >3.5, hemodynamically unstable — AASLD 2023 (Stravitz) - Transfer to transplant centre: any KCC criterion met OR INR rising despite NAC — O'Grady 1989 KCC Escalation triggers (move to higher acuity): - pH <7.3 → ICU + transplant centre + early HD eval — O'Grady 1989 KCC - INR >3 + creatinine >300 + grade III/IV HE → transplant centre now — O'Grady 1989 KCC - Lactate >3.5 mmol/L after fluid resuscitation → poor prognosis flag — Bernal 2002 - Grade III/IV HE → intubation prep — AASLD 2023 (Stravitz)
Patient Action Plan
**Acetaminophen safety plan after non-fatal overdose** Personalised values: intentional_vs_accidental, concurrent_alcohol_use, concurrent_psych_dx. **Recovery — labs normalising, NAC complete** (green): Triggers: - ALT trending downward — AASLD 2023 (Stravitz) - INR <2.0 — ACMT 2023 - No encephalopathy — AASLD 2023 (Stravitz) - Tolerating PO — NICE 2024 Actions: - Avoid all acetaminophen-containing products for at least 2 weeks — NICE 2024 - Read all labels — many combination cold/flu products contain acetaminophen — NICE 2024 - Hard cap of 3 g/day acetaminophen in healthy adults; 2 g/day if regular alcohol use or chronic liver disease — Heard NEJM 2008 - Avoid alcohol while on any acetaminophen for at least 4 weeks — AASLD 2023 (Stravitz) - Follow primary-care visit within 1 week — NICE 2024 **Caution — return precautions** (yellow): Triggers: - New nausea/vomiting — NICE 2024 - Right-upper-quadrant pain — NICE 2024 - Yellow skin or eyes — NICE 2024 - Confusion — AASLD 2023 (Stravitz) - Dark urine — NICE 2024 Actions: - Return to ED immediately — NICE 2024 - Do not take any acetaminophen — NICE 2024 - Bring all medication bottles — NICE 2024 **Crisis — psych safety + suicide prevention** (red): Triggers: - Recurrent suicidal thoughts — NICE 2024 - Plan to repeat overdose — NICE 2024 - Worsening depression — NICE 2024 Actions: - Call 988 (Suicide & Crisis Lifeline) — NICE 2024 - Go to nearest ED — NICE 2024 - Do not stay alone — contact emergency contact / family — NICE 2024 - Confirm follow-up with psychiatry within 7 days — NICE 2024
Earlier-Return Triggers
Return-precaution thresholds (watch for): - [LIFE_THREATENING] Arterial pH <7.3 after fluid resuscitation (KCC single-criterion threshold) — O'Grady 1989 KCC - [LIFE_THREATENING] INR >6.5 (PT >100s) AND creatinine >300 µmol/L AND grade III/IV HE — O'Grady 1989 KCC - [SEVERE] 4-h+ APAP level above the 150 mg/L (US) / 100 mg/L (UK) treatment line on Rumack-Matthew nomogram — Rumack-Matthew 1975
Citations
- 2023 AASLD Practice Guidance on Acute Liver Failure + 2023 ACMT NAC Duration + 2024 UK NPIS/RCEM Paracetamol Guideline + 2014/2023 EXTRIP APAP + Kings College Criteria (O'Brien 1989) [PMID:26957510](https://pubmed.ncbi.nlm.nih.gov/26957510/) - Cited evidence (PMID 30992913) [PMID:30992913](https://pubmed.ncbi.nlm.nih.gov/30992913/) Last reconciled with current guidelines: 2026-04-13.
References
- 2023 AASLD Practice Guidance on Acute Liver Failure + 2023 ACMT NAC Duration + 2024 UK NPIS/RCEM Paracetamol Guideline + 2014/2023 EXTRIP APAP + Kings College Criteria (O'Brien 1989) — PMID:26957510
- Cited evidence (PMID 30992913) — PMID:30992913