The best study addressing this question was done by the Acute liver Failure Group sponsored by the NIH. The reference is Lee et al. Gastroenterology 2009 137:856-64. The NAC was well tolerated overall with some nausea and vomiting reported. The strength of the study was that it showed that NAC when used in all cases was well tolerated and possibly effective even in the NON-acetominophen cases that were known. The key is that it can be difficult to get a good history here and in there study there was evidence that some of the Non-acetominophen cases had adjuncts with more sophisticated testing. The weakness of the study was that they only did univariate analysis. This weakness is particularly important because the study groups did not randomize equally. There was some very important differences in the groups that could have effected outcomes i.e. time to Jaundice and others - so in the end one cannot say that it was the NAC that improved survival with this major limitation. It's important to start every Fulminant case on NAC mostly because the history of acetaminophen use is not always clear and missing or starting NAC late may have dire consequences.

Thank you Dr Riley. I agree about the best reference is Lee et al at Gastroenterology. We use NAC for all FHF patients, starting at level II of HE in dosis for acetaminophen intoxication. After 48h we discontinue NAC. Some patients recover the liver function at this time, or the option of liver tx may have a better decision with a better condition.