Table 2. Clinical indications for use of NAC.

1	Severe APAP toxicity with ALT:AST > 1000
2	Initiation of NAC within 24 hours of ingestion
3	Serum APAP levels from 140 mg/L at 4 hours to 50 mg/L at 10 hours
4	Acute poisoning (ingested in 1 hour) with no other products containing acetaminophen in the past 24 hours
5	Acute poisoning with no ingestion of sustained release formulations
6	Baseline normal ALT, AST and INR
7	Used ideally within the first 8–10 hours with risk of hepatotoxicity being < 5%, especially if APAP level is above the treatment line on the Rumack-Matthew nomogram
8	Empirical use when APAP levels cannot be obtained within 8 hours of ingestion

Abbreviations: APAP, acetaminophen; ALT, alanine aminotransferase; AST, aspartate aminotransferase; INR, international normalized ratio; NAC, N-acetylcysteine.