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Educational reference only · Last reviewed: March 2026
This tool plots a serum acetaminophen level against the Rumack–Matthew nomogram to estimate whether N-acetylcysteine (NAC) treatment may be indicated.
The nomogram is only valid for: single, acute overdoses at a known time of ingestion, with a level drawn between 4 and 24 hours post-ingestion.
It is not valid for staggered/repeated ingestions, unknown ingestion time, or chronic excess ingestion.
Always contact your regional poison centre or clinical toxicology service and follow local guidelines before making treatment decisions. This tool must not be used as the sole basis for clinical care.