Revised Rumack-Matthew nomogram for the acute ingestion of acetaminophen

This nomogram should only be used after an acute acetaminophen ingestion. A serum acetaminophen concentration should be obtained 4 to 24 hours after an ingestion to ensure that a peak has occurred. The concentration should be plotted in relationship to the time of ingestion to determine the likelihood of toxicity and the need for treatment. Points on or above the treatment line indicate that acetylcysteine therapy is indicated since hepatoxicity is possible. Many experts would provide an increased dose of acetylcysteine for points on or above the high-risk line. This nomogram cannot be used if history of ingestion is unreliable or unknown or for ingestions that occurred greater than 24 hours prior to presentation, repeated supratherapeutic oral ingestions, or iatrogenic intravenous overdose. Refer to UpToDate content for advice regarding these circumstances and when to repeat serum concentrations if an extended-release formulation was ingested or there was an opioid or anticholinergic co-ingestion.