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Emerg Med J. 2007 December; 24(12): 866.
PMCID: PMC2658376

Oral N‐acetylcysteine for acute paracetamol poisoning

In the UK, a 20 h intravenous N‐acetylcysteine (NAC) regimen is the standard antidote for significant acute paracetamol poisoning. In the USA, although the Food and Drug Administration approved the use of an intravenous formulation of NAC in 2004, a 72 h oral NAC protocol is still standard practice.1 If the US experience demonstrates that oral NAC is safe and effective, then it might be reasonable occasionally to use it in the UK—for example, in cases of difficult or refused intravenous access.

A national email survey of all 64 emergency medicine consultants and registrars in Wales was performed to determine attitudes to the use of oral NAC. After a further email reminder a total of 51/64 had replied, a response rate of 80%. Only 29/51 (57%) knew about oral NAC, and only 2/51 (4%) had used it (both in the USA). Having been made aware of it, 36/51 (71%) would consider using it, particularly for cases of difficult intravenous access or needle phobia, providing there was evidence for its safety and efficacy, and it was available.

Oral NAC is available in the UK on a named patient basis, and the standard intravenous preparation can be drunk through a straw (preferably disguised in cola or juice).

No randomised controlled trial has been performed to compare oral and intravenous NAC. The 2006 Cochrane review of several case series concluded there was no clear difference in efficacy (in terms of hepatoxicity and mortality rates) between intravenous and oral routes. No studies have demonstrated any difference in safety or side effects.2

Oral NAC has been used for 30 years in the USA with similar efficacy and safety as in the UK with intravenous NAC. This survey suggests that UK emergency physicians might welcome the option to use oral NAC in certain limited circumstances, if it were more readily available.


Competing interest: None declared.


1. Prescott L. Oral or intravenous N‐acetylcysteine for acetaminophen poisoning? Ann Emerg Med 2005. 45409–413.413 [PubMed]
2. Brok J, Buckley N, Gluud C. Interventions for paracetamol (acetaminophen) overdoses. Cochrane Database Syst Rev 2006. (2)CD003328 [PubMed]

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