Key points

  • We recommend to consult your poison centre with the use of this antidote
  • In general, N-acetylcysteine (NAC) therapy must be initiated rapidly (less than 8 h) following acute poisoning. 
  • The Rumack-Matthew Nomogram (Rumack-Matthew International System of units; mcmol/L) (Rumack-Matthew Imperial units; mcg/mL) can only be used to evaluate the risk of patients presenting within 24 hours following a single ingestion of acetaminophen. For all other situations, it is strongly advised to consult your poison centre.
  • If an intravenous acetaminophen overdose has occurred or is suspected, we recommend to consult your poison centre.
  • If any of the following risk factors are present, it is strongly advised to consult your poison centre: isoniazid treatment, alcoholism (without presence of ethanol in the blood), pre-existing liver dysfunction.
  • Intravenous NAC administration can lead to decreases in clotting factors and thus increases INR. This INR elevation is mild and typically below 1.5 to 2.0.
  • It is possible that high concentrations of NAC can interfere with some capillary glucose measurements. This is more likely to occur immediately following the loading dose in any of the NAC protocols. If clinically indicated, a capillary blood glucose and a serum blood glucose should be drawn to identify discrepancy. Contact your local poison centre for advice.

© Centre antipoison du Québec, CIUSSS de la Capitale-Nationale, 2019. The information contained in this site may be cited, provided the source is acknowledged. Any use for commercial or advertising purposes is strictly prohibited.

ISSN : 2292-230X

Authors: Bailey B, Blais R, Dubé PA, Friesen M, Gaudreault P, Gosselin S, Laliberté M, Larocque A, St-Onge M

Reviewers: Duval C, Elliott A, Mackenzie C, Murphy N, Letarte A, Pursell R, Thompson M, Yarema M

Last updated : 2024-02-26