| To obtain emergency consultation with a medical toxicologist, in the United States, call 1-800-222-1222 for the nearest regional poison center. Contact information for poison centers around the world is available at the WHO website and in the UpToDate topic on regional poison centers (society guideline links). |
| Clinical presentation |
| Nausea and vomiting are common early symptoms. |
| Patients that subsequently develop liver injury and death may be asymptomatic for hours after an acute ingestion. |
| Diagnostic evaluation |
| In all patients with suspected acetaminophen poisoning, obtain the following: serum acetaminophen concentration, aminotransferases (AST, ALT), PT/INR, and basic chemistry panel (electrolytes, BUN, creatinine). |
| In all patients with a suspected intentional overdose, obtain serum salicylate concentration, fingerstick glucose, ECG, and qualitative pregnancy test in females of childbearing age. |
| Treatment |
| Secure airway, breathing, and circulation as necessary. |
| Give activated charcoal (AC) 50 g to all adult patients presenting within 4 hours of ingestion unless contraindicated; AC may be useful for co-ingestants or extended-release formulation beyond 4 hours. Pediatric AC: 1 g/kg (maximum 50 g). |
Treat with acetylcysteine if: - Serum acetaminophen concentration drawn at 4 to 24 hours after an acute ingestion is above the treatment line on the Revised Rumack-Matthew nomogram (refer to UpToDate graphic on Revised Rumack-Matthew nomogram for the acute ingestion of acetaminophen).
- Serum acetaminophen concentration is unavailable or will not return within 8 hours of time of ingestion and suspected ingestion of >150 mg/kg (7.5 g total dose regardless of weight) of acetaminophen.
- Reliable history with repeated supratherapeutic ingestion (ie, multiple ingestions during a period greater than 24 hours) and a serum acetaminophen concentrations ≥20 mcg/mL (132 micromol/L) or AST/ALT is elevated (unless the elevation is patient's baseline value).
- Unreliable history (eg, time of ingestion is unknown) and serum acetaminophen concentration >10 mcg/mL (66 micromol/L) or AST/ALT is elevated (unless the elevation is patient's baseline value).
- There is evidence of any liver injury with a history of acetaminophen ingestion.
- High-risk ingestion (reliable history of >30g acetaminophen ingestion; signs of parent-compound toxicity such as hemodynamic instability, altered mental status, metabolic acidosis early following ingestion; acetaminophen concentration above the high-risk line on the Revised Rumack-Matthew nomogram).
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IV dosing of acetylcysteine: - Many protocols exist. For a patient with an acute ingestion, whichever is chosen should deliver at least 300 mg/kg acetylcysteine during the first 20 to 24 hours of treatment. For a patient with repeated supratherapeutic ingestion or an unreliable history with detectable acetaminophen concentration, the acetylcysteine regimen should be continued for at least 12 hours.
- We suggest the 2-bag protocol: 200 mg/kg (maximum 20 g) over 4 hours (50 mg/kg per hour), followed by 100 mg/kg (maximum 10 g) over 16 hours (6.25 mg/kg per hour).
- Another common protocol involves 3 bags: 150 mg/kg loading dose (maximum 15 g) over 60 minutes, followed by 50 mg/kg (maximum 5 g) over 4 hours (12.5 mg/kg per hour), followed by 100 mg/kg (maximum 10 g) over 16 hours (6.25 mg/kg per hour).
- Patients weighing <41 kg: Use reduced diluent volume (refer to UpToDate content on IV acetylcysteine dilution in children).
- Either protocol should be followed by a continuous IV infusion at 6.25 mg/kg per hour until stopping criteria are met.
- IV dosing is acceptable in all cases of acetaminophen toxicity but should be used instead of oral dosing in patients unable to tolerate oral acetylcysteine (eg, intractable vomiting), patients with a medical condition precluding administration of oral acetylcysteine (eg, corrosive ingestion, gastrointestinal bleed), high-risk ingestion, signs of parent compound toxicity, patients with hepatic failure, and pregnant patients.
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Oral dosing of acetylcysteine: - Oral dosing is acceptable for non-pregnant patients with a functional gastrointestinal tract and no evidence of hepatic failure.
- Dilute 20% solution 1:3 to prepare 5% solution for oral use:
- Loading dose of 140 mg/kg (maximum 14 g), followed by 70 mg/kg (maximum 7 g per dose) every 4 hours until stopping criteria are met.
- If vomiting occurs within 1 hour of acetylcysteine dosing, a full dose should be repeated as rapidly as possible.
- Treat nausea/vomiting: Ondansetron 4 to 8 mg oral/IV.
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| All of the following criteria should be met to stop acetylcysteine treatment: INR is <2, AST/ALT are normal or have decreased 25 to 50% from the peak, serum acetaminophen concentration <10 mcg/mL (66 micromol/L), and the patient is clinically well. |
September 2025
