Rumack-Matthew Nomogram
Determines need for N-acetylcysteine (NAC) treatment following paracetamol (acetaminophen) overdose based on serum level and time post-ingestion
Score interpretation
A paracetamol level taken less than 4 hours after ingestion cannot be plotted on the treatment line.
→ Repeat the level at 4 hours or later after ingestion; follow TOXBASE for when to start treatment before the level.
Level below the UK single treatment line (100 mg/L at 4 h, 15 mg/L at 15 h) for the time since ingestion.
→ Acetylcysteine not indicated by the line. Clinical review — if ALT is raised or the patient has symptoms, follow TOXBASE.
Level on or above the UK single treatment line (MHRA 2012: treat regardless of risk factors).
→ Start intravenous acetylcysteine per TOXBASE / local protocol. Check INR, ALT, creatinine and acid–base; seek National Poisons Information Service advice if needed (UK: 0344 892 0111).
The treatment line cannot be used for a staggered overdose or when the time of ingestion is uncertain (MHRA 2012).
→ Treat per TOXBASE / National Poisons Information Service guidance.
Interpretation bands for the Rumack-Matthew. Apply clinical judgement and local guidance.
References
- Rumack BH, Matthew H. Acetaminophen poisoning and toxicity. Pediatrics. 1975;55(6):871–876.
- TOXBASE / NPIS. Paracetamol Overdose Treatment Guidelines. 2023.
- MHRA. Treating paracetamol overdose with intravenous acetylcysteine: new guidance. Drug Safety Update, September 2012.
Related
Curated clinical cross-links plus same-class fallbacks.
- Acetylcysteine (N-acetylcysteine — Paracetamol Overdose) · Mucolytic / Hepatoprotective Antidote
- Acetylcysteine (N-acetylcysteine — NAC) · Antidote — paracetamol overdose / Hepatoprotectant
- Acetylcysteine · Mucolytic / Paracetamol overdose antidote
- Dobutamine (Acute HF / Stress Echo) · Inotrope / Acute Heart Failure
- Milrinone · Inodilator / Acute Heart Failure
- Vericiguat · Heart Failure
- Difficult Airway Algorithm (DAS) · DAS 2015; Royal College of Anaesthetists
- Major Haemorrhage Protocol · NICE NG24; UK MHP guidelines
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
- Ventricular Tachycardia / Fibrillation · Resuscitation Council UK ACLS; ESC 2022 Ventricular Arrhythmia Guidelines
Featured in these MRCEM clinical pathways
The Rumack-Matthew is covered in detail — with RCEM/NICE evidence base, indications and pitfalls — in the following exam-focused pathways on our sister siteReviseMRCEM.
MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.