Tylenol Overdose Risk Calculator
Evaluate mg/kg ingestion and timing to determine if N-acetylcysteine is indicated per Rumack-Matthew nomogram guidance.
Sum all acetaminophen from tablets/liquids.
For multiple ingestions, use time since last large ingestion.
Risk Summary
Dose per kg
142.9 mg/kg
- Total dose exceeds 4 g/24 h (adult max).
Recommended Actions
• Draw acetaminophen level ≥4 hours post ingestion and plot on Rumack-Matthew nomogram.
• If line intersected or cannot obtain level within 8 hours, start N-acetylcysteine (NAC).
How to Use This Calculator
Collect ingestion history
Determine total mg taken and the timing of ingestion(s). Include OTC combinations.
Obtain acetaminophen level
Draw at ≥4 hours post ingestion for Rumack-Matthew nomogram plotting. Repeat if uncertain timing.
Start NAC when indicated
Initiate N-acetylcysteine if level plots above treatment line or if >8 hours since ingestion while awaiting results.
Formula
mg/kg ingestion = Total dose (mg) ÷ weight (kg).
Reference: Rumack BH, Matthew H. Pediatrics. 1975; AAP Guidelines for Acetaminophen Poisoning.
Frequently Asked Questions
What if ingestion was staggered?
Nomogram is for single acute ingestion. For repeated supratherapeutic doses, start NAC if >150 mg/kg/day or LFTs elevated.
Can I stop NAC early?
After 12–21 hours, stop if acetaminophen undetectable and LFTs normalizing; otherwise continue.
IV vs oral NAC?
Both effective; IV preferred if vomiting, fulminant hepatic failure, or high-risk patients.
What labs to monitor?
Acetaminophen level, AST/ALT, INR/PT, creatinine, electrolytes. Repeat every 12–24 hours.
When to transfer?
Transfer if INR >2, AST/ALT quadruple baseline, encephalopathy, or metabolic acidosis—evaluate for liver transplant center.